In vitro protein fractions. Whey protein fractions

Under the influence of an electric field (electrophoresis is used in practice), the protein is divided into 5-6 fractions, which differ in location, mobility, structure and proportion in the total protein mass. The most important fraction (albumin) is more than 40-60% of the total protein in blood serum.

These include acute phase (rapid response) proteins:

• antitrypsin promotes fibrillogenesis (the process of formation of connective tissue);
• lipoproteins are responsible for delivering lipids to other cells;
• transport proteins bind and move important body hormones (cortisol, thyroxine).

Also includes acute phase proteins:

• macroglobulin activates the body's defense processes in infectious and inflammatory lesions;
• haptoglobin binds to hemoglobin;
• ceruloplasmin determines and binds copper ions, neutralizes free radicals and is an oxidative enzyme for vitamin C, adrenaline;
• lipoproteins provide movement of fats.

This group includes proteins:

• transferrin (provides the movement of iron);
• hemopexin (prevents iron loss);
• complements (participate in the immune response);
• beta-lipoproteins (move phospholipids and cholesterol);
• some immunoglobulins (also provide an immune response).

The fraction includes the most important immunoglobulin proteins of different classes (IgA, IgM, IgE, IgG), which are antibodies and are responsible for the local immunity of the body.

As a result of the development of acute or exacerbation of chronic inflammatory diseases the ratio of protein fractions changes. A decrease in the amount of one or another type of protein can be observed with immunodeficiencies, which indicate serious processes in the body (autoimmune diseases, HIV, oncology, etc.).

Excess often indicates monoclonal gammopathy (production of abnormal types of immunoglobulins). The consequences of gammopathy include multiple myeloma (plasma cell cancer), Waldenström's macroglobulinemia (tumor bone marrow) etc. Polyclonal gammopathy (secretion of abnormal amounts of immunoglobulins) may also occur. The result is infectious diseases, autoimmune pathologies, liver diseases (for example, viral hepatitis) and other chronic processes.

AT biochemical analysis fractions of blood proteins reflect the state of protein metabolism.

Such a diagnosis is important for many diseases, so it’s worth understanding what protein fractions are and what values ​​\u200b\u200bare considered normal.

Plasma protein

Human blood plasma includes about a hundred different protein components (fractions). Most of them (up to 90%) are albumins, immunoglobulins, lipoproteins, fibrinogen.

The remainder includes other protein components present in plasma in small amounts.

The blood serum contains approximately 7% of all proteins, and their concentration reaches 60 - 80 g / l. The value of fractions in the blood is enormous.

Proteins provide an ideal acid-base balance of the blood, are responsible for the transport of substances, and control blood viscosity. Proteins play an important role in the circulation of blood through the vessels.

Basically, the protein fractions of the blood are produced by the liver (fibrinogen, albumins, part of the globulins). The remaining globulins (immunoglobulins) are synthesized by RES cells in the bone marrow and lymph.

The composition of the total protein of blood plasma includes albumins and globulins, which are in the established qualitative and quantitative proportions. In accordance with the research method, a different amount and type of protein fractions are isolated.

A blood test for protein fractions is most often carried out by electrophoretic fractionation. There are several types of electrophoresis depending on the supporting medium.

So, when analyzing on a film or gel, the following protein fractions of blood plasma are isolated: albumin (55–65%), α1-globulin (2–4%), α2-globulin (6–12%), β-globulin (8–12 %), γ-globulin (12–22%).

The essence of the method is to estimate the intensity of the bands of fractions in the total amount of protein. Protein fractions are presented in the form of bands of different widths and specific arrangements.

In clinical diagnostic laboratories, such a study is most often carried out.

A greater number of fractions of blood proteins are found when using other media for electrophoretic research.

For example, starch gel analysis can isolate up to 20 protein fractions. In the course of modern examinations (radial immunodiffusion, immunoelectrophoresis, etc.), many individual proteins are found in the composition of globulin fractions.

In some pathologies, electrophoretic examination changes the ratio of protein fractions compared to normal values. Such changes are called dysproteinemia.

Regardless of the presence of standard deviations in such analyzes, which make it possible to diagnose pathology quite often with confidence, usually the result of protein electrophoresis is not accepted as an unambiguous basis for making a diagnosis and selecting a treatment regimen.

Therefore, the interpretation of the analysis is carried out in conjunction with other additional clinical and laboratory studies.

Albumins are simple, water-soluble proteins. Most known species albumin - serum albumin. The fraction is produced by the liver and makes up about 55% of all proteins contained in blood plasma.

Normal level serum albumin in adults is in the range of 35 - 50 g / l. For children under the age of three years, normal values ​​​​are from 25 to 55 g / l.

Albumin is produced by the liver and depends on the supply of amino acids. The main functions of the protein are considered to be the maintenance of plasma oncotic pressure and the control of BCC.

In addition, albumin in conjunction with bilirubin, cholesterol, acids and other substances is involved in the metabolism of minerals and hormones.

Fraction controls the content of free substances, non-protein fractions. This function of albumin allows it to be included in the process of detoxification of the body.

Globulins are protein fractions of blood serum, which have a higher molecular weight and lower solubility in water, unlike albumins. Fractions are produced by the liver and the immune system.

Alpha1-globulins (prothrombin, transcortin, etc.) are responsible for the transport of cholesterol, cortisol, progesterone and other substances.

In addition, fractions take part in the process of blood clotting (second phase). The normal content of alpha1-globulins in the blood serum is from 3.5 to 6.5% (from 1 to 3 g / l).

At the same time, in children, the concentration of plasma protein fractions is slightly different: up to 6 months, values ​​​​from 3.2 to 11.7% are considered the norm, with age the upper limit drops and by 7 years reaches the norm in adults.

Alpha2-globulins (antithrombin, vitamin D, binding protein, etc.) carry out the transport of copper, retinol, calciferol ions.

The normal value of protein fractions of blood plasma in adults is in the range of 9 - 15% (from 6 to 10 g / l). In children under 18 years of age, the concentration is considered to be from 10.6 to 13%.

Beta-globulins (transferrin, fibrinogen, binding protein globulin, etc.) are responsible for the transport of cholesterol, iron ions, vitamin B12, and testosterone.

Beta globulins are involved in the first phase of the blood clotting process. In adults, the accepted norm for the concentration of fractions in plasma is from 8 to 18% (from 7 to 11 g / l). For childhood a decrease in the level of protein in the blood to 4.8 - 7.9% is characteristic.

Gamma globulins (IgA, IgG, IgM, IgD, IgE) are antibodies and B-lymphocyte receptors that provide humoral immunity.

normal value for adults, the concentration of gamma globulins in the blood is considered to be from 15 to 25% (from 8 to 16 g / l). In children, a decrease in the level of protein fractions to 3.5% (under the age of six months) and up to 9.8% (under the age of 18 years) is acceptable.

The study of protein fractions is important in the diagnosis of many diseases. Lack or excess of one of the types of protein disrupts the balance of blood plasma. In laboratories, there are 10 types of electrophoregrams that correspond to certain pathologies.

The first type is acute inflammation. These pathologies (pneumonia, pulmonary tuberculosis, sepsis, myocardial infarction) are characterized by a significant decrease in the level of albumin and an increase in the concentration of alpha1-, alpha2- and gamma-globulins.

The second type of electropherograms - chronic inflammation(eg, endocarditis, cholecystitis, and cystitis). In the analysis, a decrease in the level of albumin and a significant increase in the number of alpha2 and gamma globulins will be noticeable. The level of alpha1- and beta-globulins will remain within the normal range.

The third type is responsible for violations of the renal filter (albumin and gamma globulin fall against the background of an increase in the concentration of alpha2 and beta globulins).

The fourth type is the most striking marker of the presence of malignant tumors and metastatic neoplasms.

With this pathology, the analysis demonstrates a marked decrease in the level of albumin and a simultaneous increase in all globulin components of the protein. The location of the primary tumor does not affect the performance of the analysis.

The fifth and sixth types indicate the presence of hepatitis, liver necrosis and some forms of polyarthritis. Against the background of a decrease in the concentration of albumin, an increase in gamma globulin and slight deviations from the norm of beta globulin are noticeable.

The seventh type of proteinogram signals the development of jaundice various genesis. The fall in the level of albumin occurs with a simultaneous increase in the number of alpha2-, beta- and gamma-globulins.

The eighth, ninth and tenth types are responsible for multiple myeloma of various origins. With a decrease in the concentration of albumin, an increase in globulin indicators is noted (each type has its own).

Deciphering the indicators of proteinograms is carried out only by a specialist. Many features of the interpretation of the analysis, depending on the patient's condition and the data of other examinations, do not allow the use of an electrophoregram as a direct diagnosis.

An analysis of the protein composition of the blood is prescribed for inflammatory processes in acute or chronic form(any infections, pathologies immune system, collagenoses, etc.).

Plasma testing is performed on patients suspected of having multiple myeloma and various paraproteinemias.

Plasma protein

Indications

The study of protein fractions allows diagnosing immunodeficiency syndrome, oncological and autoimmune processes.

Also, the doctor may prescribe a proteinogram in the following cases:

• assessment of the severity of the course of inflammatory or infectious processes (in acute and chronic form);
• diagnosis of diseases of the liver (hepatitis) and kidneys (nephrotic syndrome);
• determination of the duration of the disease, form (acute, chronic), stage, as well as monitoring the effectiveness of therapy;
• diagnostics of mono- and polyclonal gammopathy;
• diagnosis and treatment of diffuse lesions of the connective tissue, including collagenoses (its systemic destruction);
• observation of patients with impaired metabolism, diet;
• monitoring the condition of patients with malabsorption syndrome (impaired digestion and absorption of nutrients);
• suspicion of multiple myeloma, characterized by symptoms: chronic weakness, fever, frequent fractures and displacements, bone aches, infectious processes in a chronic form.

The study of protein fractions in the blood (proteinogram) reveals the concentration of total protein, the quantitative ratio of albumins and globulins.

An analysis for protein fractions is prescribed during the second stage of a comprehensive examination based on the results of the identified deviations in clinical and biochemical parameters. The analysis is indicated for pathological bone fractures, increased calcium in the blood, anemia. Such symptoms may indicate the development of osteoporosis associated with the accumulation of paraprotein in the bones in myeloma.

The study of protein fractions is indicated for unexplained weakness, prolonged fever, frequent colds. These symptoms appear due to a decrease in the level of globulin fraction in plasma and the development of an immunodeficiency state. The analysis is carried out in order to differential diagnosis diseases of the liver and kidneys, congenital insufficiency of certain protein fractions, endocrine diseases.

After X-ray examination with contrast, hemodialysis procedures and plasmapheresis, a week delay in the study is required.

Biochemical analysis reflects:

• liver condition (enzymes alanine aminotransferase - ALAT, aspartate aminotransferase - ASAT, bilirubin);
• biliary tract (bilirubin, alkaline phosphatase);
• kidneys (urea, creatinine, uric acid);
• heart and blood vessels (fractions of the enzyme lactate dehydrogenase);
• lipid metabolism (lipid spectrum);
• protein metabolism(protein fractions);
• inflammatory indicators ( C-reactive protein, sialic acids);
• glucose level.

Firstly, this analysis is prescribed when a person is admitted for treatment to a hospital as part of monitoring the basic functions of the body. Some indicators can be taken in expanded form, for example, the lipid spectrum, if the disease profile requires it. Otherwise, the minimum set includes the determination of total protein, glucose, liver enzymes, creatinine, bilirubin, and, if inflammation is suspected, C-reactive protein.

Secondly, biochemistry is done when contacting a clinic and private centers to specialists as the next stage of diagnosis. This analysis may be required for lesions of almost all organs and systems, only the emphasis on one or another group of indicators will differ.

Thirdly, biochemical indicators necessary to monitor efficacy and safety drug therapy, for example, steroids, cytostatics, hormones.

Also, prophylactic biochemistry is prescribed when monitoring certain population groups (pregnant women as part of screening).

Acute inflammatory diseases.

Chronic inflammatory diseases.

Interpretation of results

If the patient received the results biochemical research blood, and the protein content is different from normal, then you should not worry much. It is important to remember if there were any stresses the day before. If yes, then you need to ask the doctor for a referral for re-analysis.

A slight decrease in albumin can also be observed:

• During pregnancy;
• With an overdose of drugs;
• With a prolonged increase in temperature;
• At smokers.

Due to the large number possible violations the albumin count is not of significant diagnostic value, but rather is a reference. More important is the decoding of globulins, the increase and decrease in the level of which, much more accurately indicates specific pathologies.

These protein fractions are decisive for:

• Protective properties of the body;
• The quality of blood clotting;
• Transfer of vitamins, hormones and other useful components through the tissues of the human body.

It is in connection with this that the norm of globulins has importance when deciphering the analysis of serum for the percentage of various protein fractions. If a change in the normal amount of alpha-1 globulins is detected during the analysis of blood serum, then this is a very serious sign that may indicate the development of oncological diseases, the presence of infection and inflammatory processes. A decrease in the level of alpha-1 globulins often occurs against the background of:

• Emphysema affecting lung tissue;
• Pathology of the kidneys.

The number of alpha-1 globulins increases with:

• Pregnancy, which is accompanied by pathologies of the fetus;
• Hormonal imbalance;
• Systemic lupus erythematosus.

Indicative for the diagnosis is an increased rate of beta-globulins. First of all, it is a confirming factor for the presence of liver pathologies and development malignant formations. Decreased beta globulins in combination with other studies may confirm:

• Violations at work endocrine system;
• The presence of inflammatory processes in the body;
• Anemia.

Gamma globulins reflect the overall state of the immune system. A significant decrease in their level may indicate AIDS. In addition, a deviation from the norm confirms the presence allergic reactions and chronic inflammatory processes.

are of great diagnostic value quantitative relationships between individual serum proteins. For the separation of all serum proteins, an electrophoresis method is used, based on the different mobility of serum proteins in an electric field.
Using electrophoresis, proteins are divided into the following fractions: albumins and globulin fractions (alpha1-globulins, alpha2-globulins, beta-globulins and gamma-globulins):

1. Alpha1 globulins: alpha1-antitrypsin, alpha1-acid glycoprotein, alpha-1 lipoprotein.
2. Alpha2 globulins: alpha2-macroglobulin, haptoglobin, apolipoproteins, ceruloplasmin.
3. Beta globulins: transferrin, C3 component of the complement system, beta-lipoproteins, hemopexin.
4.Gamma globulins: immunoglobulins - IgA, IgM, IgG.

As a result of the development of acute or exacerbation of chronic inflammatory diseases, the ratio of protein fractions changes.
A decrease in the amount of one or another type of protein is observed with immunodeficiencies, which indicate serious processes in the body (autoimmune diseases, HIV, oncology, etc.). An excess of one or another type of protein indicates monoclonal gammopathy (production of abnormal types of immunoglobulins). The consequences of gammopathy include multiple myeloma (plasma cell cancer), Waldenström's macroglobulinemia (bone marrow tumor), etc.

The study of protein fractions is more diagnostically informative than the determination of total protein or albumin alone. In many diseases, the percentage of protein fractions often changes, although the total protein content in the blood serum remains within the normal range.
In some diseases, proteins appear in the blood that differ physically, chemically and immunologically from the usual blood serum proteins. They are called monoclonal immunoglobulins (paraproteins, M-proteins). During electrophoresis of blood serum proteins, the presence of paraproteins is evidenced by the appearance of an additional electrophoregram (in healthy people absent) of a narrow and sharply limited fraction of proteins (also called the M-gradient) in the region of gamma globulins.
The detection of paraproteins is most characteristic of paraproteinemic hemoblastoses ( myeloma, Waldenström's macroglobulinemia, heavy chain disease), is less common in chronic hepatitis, in some elderly patients. High concentrations of C-reactive protein and fibrinogen can mimic the M-protein.

Increase in alpha-1 and alpha-2 globulins can be observed in acute and exacerbations of chronic inflammatory processes, with diffuse diseases connective tissue (systemic lupus erythematosus, rheumatism, rheumatoid arthritis and etc.), malignant tumors, some kidney diseases occurring with nephrotic syndrome (glomerulonephritis, amyloidosis, etc.).

Decreased levels of alpha-2 globulins can be observed in chronic pancreatitis, diabetes mellitus, less often in toxic hepatitis. An increase in the content of beta-globulins most often occurs in people with impaired lipid (fat) metabolism, including patients with atherosclerosis, ischemic disease heart, hypertension.

Decrease in beta globulins is less common and is usually due to a general deficiency of plasma proteins.

Increasing the amount of gamma globulins , which are the main "suppliers" of antibodies, is often observed in chronic liver diseases (chronic hepatitis, cirrhosis), chronic infections, some autoimmune diseases (rheumatoid arthritis, chronic autoimmune hepatitis, etc.), myeloma.

Indications for the appointment of the study

Study preparation

GENERAL RULES:

1. For most studies, it is recommended to donate blood in the morning, between 8 a.m. and 11 a.m., on an empty stomach (at least 8 hours should elapse between the last meal and blood sampling, you can drink water as usual), on the eve of the study, a light dinner with a restriction reception fatty foods. For infection tests and emergency investigations, it is acceptable to donate blood 4-6 hours after the last meal.

2. ATTENTION! Special preparation rules for a number of tests: strictly on an empty stomach, after 12-14 hours of fasting, you should donate blood for gastrin-17, lipid profile (total cholesterol, HDL cholesterol, LDL cholesterol, VLDL cholesterol, triglycerides, lipoprotein (a), apolipo-proten A1, apolipoprotein B); a glucose tolerance test is performed in the morning on an empty stomach after 12-16 hours of fasting.

3. On the eve of the study (within 24 hours), exclude alcohol, intense physical exercise, reception medicines(by agreement with the doctor).

4. 1-2 hours before donating blood, refrain from smoking, do not drink juice, tea, coffee, you can drink non-carbonated water. Eliminate physical stress (running, fast climbing stairs), emotional arousal. It is recommended to rest and calm down 15 minutes before donating blood.

5. You should not donate blood for laboratory research immediately after physiotherapy procedures, instrumental examination, x-ray and ultrasound examinations, massage and other medical procedures.

6. When monitoring laboratory parameters in dynamics, it is recommended to conduct repeated studies under the same conditions - in the same laboratory, donate blood at the same time of day, etc.

7. Blood for research should be donated before the start of taking medications or no earlier than 10-14 days after they are discontinued. To evaluate the control of the effectiveness of treatment with any drugs, it is necessary to conduct a study 7-14 days after the last dose of the drug.

If you are taking medication, be sure to tell your doctor about it.

Human serum albumin

Albumins and globulins are the main groups of plasma proteins. Analysis for individual protein fractions serves as a marker of protein metabolism disorders, allows you to identify various pathologies, monitor changes in diseases, and choose an effective treatment strategy.

Albumins (A) perform many tasks in the human body: maintain oncotic blood pressure, ensure the integrity of vascular barriers; transport fatty acids, hormones, vitamins; bind to derivatives of various substances, limiting their harmful effects on cells; interact with coagulation factors, serve as a source of amino acids.

Globulin structure

Globulins (G) are a heterogeneous group:

• α1-G: transfer lipids, acids, hormones; participate in coagulation processes, inhibit various enzymes.
• α2-G: bind hemoglobin and enzymes, transport vitamins and copper atoms, regulate coagulation processes.
• β-G: transport lipids and iron; bind to sex hormones, proteins and other elements.
• γ-G: predominantly are immunoglobulins, the main function of which is to neutralize harmful agents that enter the body.

Norms for protein fractions

The analysis takes into account the albumin / globulin ratio

The analysis takes into account the ratio of fractions A / G, the norm of this value = 1: 2.

Reference values ​​for the albumin fraction.

The norm for the fraction of globulins.

Guideline values ​​may vary depending on the laboratory.

Deviations from the norm: reasons for the increase and decrease

Intestinal infections can cause dehydration

Increase in albumin level:

• dehydration,
• infectious infections,
• extensive burns and injuries.

Decreased albumin level:

In autoimmune diseases, gamma globulins increase

Elevated globulins:

• α1-G: exacerbation chronic diseases, liver tissue damage;
• α2-G: acute inflammatory processes (kidney pathologies, pneumonia, etc.);
• β-G: lipid metabolism disorders, diseases of the liver, kidneys, stomach;
• γ-G: inflammation, infection, hepatitis, autoimmune diseases, malignant pathologies.

Decreased level of globulins:

• α1-G: deficiency of proteins of this fraction;
• α2-G: diabetes, hepatitis;
• β-G: reduced level of fi-proteins;
• γ-G: suppression of the immune system.

Indications for analysis

There are a number of indications for the appointment of a study

Analysis is assigned in the following cases:

• as a comprehensive examination.
• In diseases associated with diffuse lesions of the connective tissue.
• Infectious diseases in acute and chronic periods.
• Suspicion of a syndrome of insufficient absorption of nutrients.
• With autoimmune pathologies.
• With diseases of the liver, kidneys.
• For differentiation of puffiness.
• Identification of malignant processes.

Test preparation

Preparing for the test ensures reliable results

Proper preparation for analysis allows you to get correct results.

1. The last meal should be completed 8 hours before the study, but the fasting period should not exceed 14 hours. Recommended to drink clean water excluding any drinks.
2. Do not drink alcohol the day before blood sampling, smoking is limited one hour before the analysis.
3. On the eve of the test, you should not overload the body emotionally and physically, it is better to postpone going to the gym.
4. All other studies (radiography, ultrasound) are carried out after the analysis.
5. Blood sampling is done in the morning.
6. The result of the analysis for protein fractions is affected by hormonal preparations, including oral contraceptives, as well as cytostatic agents. If it is impossible to exclude their intake, it is necessary to provide a list of drugs to the doctor.

Methods for determination of protein fractions

The study of protein fractions is carried out by several methods

The following methods are used to separate proteins into fractions:

• Salting out. The technique is based on the ability of proteins to precipitate in the presence of salt solutions.
• Kohn method. Separation into fractions at a temperature of -3 to -5°C during the interaction of different concentrations of ethanol.
• Immunological: immunoprecipitation, immunoelectrophoresis, radial immunodiffusion. The techniques are based on the immune properties of protein fractions.
• Chromatography. Separation occurs in a certain adsorbent layer. The method includes: ion exchange, affinity, partition and adsorption chromatography.
• Azotometric. Fractionation is done by destroying the protein with sulfuric acid.
• Fluorimetric. The method is based on the measurement of the fluorescence of a protein labeled with fluorescamine.

The most popular methods at present are:

• Electrophoresis. The technique is based on the difference in the rate of protein mobility in an electric field.
• Colorimetry. The intensity of the light flux passing through the colored solution is measured.

Interpretation of results

The interpretation of the results is carried out by a specialist

The analysis may reveal a change in total plasma protein. In this case, it is necessary to investigate, due to which faction the change occurred.

Hyperproteinemia is an increase in total protein. If at the same time the number of γ-G is increased, the doctor may suspect an infectious infection. An increased concentration of β-G most often indicates pathological processes in the liver. Acute phase proteins belong to α-G, their growth indicates an intense inflammatory process.

Hypoproteinemia - a decrease in the level of total protein. If the decrease occurs due to α-G fractions, the presence of destructive processes in the liver and pancreas is suspected. Indicative is the deficiency of the γ-G fraction, which is typical for the depletion of the immune system in chronic pathologies, malignant neoplasms. A decrease in β-G may indicate an unbalanced diet with diets, pathologies of the digestive tract.

Paraproteinemia - the formation of non-standard proteins (paraproteins), which will increase the γ-G fraction and will indicate a number of oncological diseases, autoimmune pathologies.

Defectoproteinemia - the absence of any protein, most often as a result of a violation of protein synthesis. For example, the α2-G fraction can be reduced due to a lack of ceruloplasmin, as a consequence of the presence of Wilson's disease.

Liver disease can lead to dysproteinemia

Dysproteinemia is a violation of the quantitative ratio between protein fractions. At the same time, the level of total protein remains normal. For example, in liver diseases, albumins decrease, globulins (due to γ-G) increase.

Thus, the result of the analysis must be considered as a whole, taking into account the correlation of the values ​​of individual fractions.

The blood plasma contains 7% of all body proteins at a concentration of 60 - 80 g / l. Plasma proteins perform many functions. One of them is to maintain osmotic pressure, as proteins bind water and keep it in the bloodstream. Plasma proteins form the most important buffer system of the blood and maintain blood pH in the range of 7.37 - 7.43. Albumin, transthyretin, transcortin, transferrin and some other proteins perform a transport function. Plasma proteins determine blood viscosity and therefore play an important role in hemodynamics circulatory system. Blood plasma proteins are a reserve of amino acids for the body. Immunoglobulins, blood coagulation proteins, α 1 -antitrypsin and complement system proteins perform a protective function. By electrophoresis on cellulose acetate or agarose gel, blood plasma proteins can be separated into albumins (55-65%), α 1 -globulins (2-4%), α 2 -globulins (6-12%), β-globulins (8-12 %) and γ-globulins (12-22%). The use of other media for the electrophoretic separation of proteins makes it possible to detect a greater number of fractions. For example, during electrophoresis in polyacrylamide or starch gels, 16-17 protein fractions are isolated in blood plasma. The immunoelectrophoresis method, which combines electrophoretic and immunological methods of analysis, makes it possible to separate blood plasma proteins into more than 30 fractions. Most whey proteins are synthesized in the liver, but some are also produced in other tissues. For example, γ-globulins are synthesized by B-lymphocytes, peptide hormones are mainly secreted by cells of the endocrine glands, and the peptide hormone erythropoietin is secreted by kidney cells. Many plasma proteins, such as albumin, α 1 -antitrypsin, haptoglobin, transferrin, ceruloplasmin, α2-macroglobulin and immunoglobulins, are characterized by polymorphism.

Almost all plasma proteins, with the exception of albumin, are glycoproteins. Oligosaccharides attach to proteins by forming glycosidic bonds with the hydroxyl group of serine or threonine, or by interacting with the carboxyl group of asparagine. The terminal residue of oligosaccharides in most cases is N-acetylneuraminic acid combined with galactose. Vascular endothelial enzyme neuraminidase hydrolyzes the bond between them, and galactose becomes available for specific hepatocyte receptors. By euddcytosis, "aged" proteins enter the liver cells, where they are destroyed. T 1/2 of blood plasma proteins ranges from several hours to several weeks. In a number of diseases, there is a change in the ratio of the distribution of protein fractions during electrophoresis compared to the norm. Such changes are called dysproteinemias, but their interpretation often has a relative diagnostic value. For example, a decrease in albumin, α 1 - and γ-globulins, characteristic of nephrotic syndrome, and an increase in α 2 - and β-globulins are also noted in some other diseases accompanied by loss of proteins. With a decrease in humoral immunity, a decrease in the fraction of γ-globulins indicates a decrease in the content of the main component of immunoglobulins - IgG, but does not reflect the dynamics of changes in IgA and IgM. The content of some proteins in the blood plasma can increase sharply in acute inflammatory processes and some other pathological conditions (trauma, burns, myocardial infarction). Such proteins are called acute phase proteins , as they take part in the development of the inflammatory response of the body. The main inducer of the synthesis of most acute phase proteins in hepatocytes is the interleukin-1 polypeptide released from mononuclear phagocytes. The acute phase proteins are C-reactive protein , so called because it interacts with pneumococcal C-polysaccharide, α 1 -antitrypsin, haptoglobin, acid glycoprotein, fibrinogen. It is known that C-reactive protein can stimulate the complement system, and its concentration in the blood, for example, during an exacerbation of rheumatoid arthritis, can increase 30 times compared to the norm. Plasma protein α 1 -antitrypsin can inactivate some proteases released in the acute phase of inflammation.

Albumen. The concentration of albumin in the blood is 40-50 g/l. About 12 g of albumin is synthesized per day in the liver, T 1/2 of this protein is approximately 20 days. Albumin consists of 585 amino acid residues, has 17 disulfide bonds and has a molecular weight of 69 kD. The albumin molecule contains many dicarboxylic amino acids, therefore, it can retain Ca 2+, Cu 2+, Zn 2+ cations in the blood. About 40% of albumin is contained in the blood and the remaining 60% in the intercellular fluid, however, its concentration in plasma is higher than in the intercellular fluid, since the volume of the latter is 4 times greater than the plasma volume. Due to its relatively small molecular weight and high concentration, albumin provides up to 80% of the osmotic pressure of the plasma. With hypoalbuminemia, the osmotic pressure of blood plasma decreases. This leads to an imbalance in the distribution of extracellular fluid between the vascular bed and the intercellular space. Clinically, this manifests itself as edema. The relative decrease in blood plasma volume is accompanied by a decrease in renal blood flow, which causes stimulation of the reninangiotensinaldrsterone system, which ensures the restoration of blood volume. However, with a lack of albumin, which should retain Na +, other cations and water, water escapes into the intercellular space, increasing edema. Hypoalbuminemia can also be observed as a result of a decrease in albumin synthesis in liver diseases (cirrhosis), with increased capillary permeability, with protein losses due to extensive burns or catabolic conditions (severe sepsis, malignant neoplasms), with nephrotic syndrome accompanied by albuminuria, and starvation. Circulatory disorders, characterized by a slowdown in blood flow, lead to an increase in the flow of albumin into the intercellular space and the appearance of edema. A rapid increase in capillary permeability is accompanied by a sharp decrease in blood volume, which leads to a drop in blood pressure and is clinically manifested as shock. Albumin is the most important transport protein. It transports free fatty acids, unconjugated bilirubin Ca 2+ , Cu 2+ , tryptophan, thyroxine and triiodothyronine. Many drugs (aspirin, dicoumarol, sulfonamides) bind to albumin in the blood. This fact must be taken into account in the treatment of diseases accompanied by hypoalbuminemia, since in these cases the concentration of free drug in the blood increases. In addition, it should be remembered that some drugs can compete for binding sites in the albumin molecule with bilirubin and with each other.

Transthyretin (prealbumin ) called thyroxin-binding prealbumin. It is an acute phase protein . Transthyretin belongs to the albumin fraction, it has a tetrameric molecule. It is capable of attaching a retinol-binding protein in one binding site, and up to two thyroxine and triiodothyronine molecules in the other.

The connection with these ligands occurs independently of each other. In the transport of the latter, transthyretin plays a significantly smaller role than thyroxine-binding globulin.

α 1 - Antitrypsin belong to α 1 -globulins. It inhibits a number of proteases, including the enzyme elastase, which is released from neutrophils and destroys the elastin of the lung alveoli. Insufficiency of α 1 -antitrypsin can cause emphysema and hepatitis, leading to cirrhosis of the liver. There are several polymorphic forms of α 1 -antitrypsin, one of which is pathological. In humans homozygous for two defective alleles of the antitrypsin gene, α 1 -antitrypsin is synthesized in the liver, which forms aggregates that destroy hepatocytes. This leads to a violation of the secretion of this protein by hepatocytes and to a decrease in the content of α 1 -antitrypsin in the blood.

Haptoglobin makes up about a quarter of all α 2 -globulins. Haptoglobin during intravascular hemolysis of erythrocytes forms a complex with hemoglobin, which is destroyed in RES cells. While free hemoglobin, which has a molecular weight of 65 kD, can filter through or aggregate into the renal glomeruli, the hemoglobin-haptoglobin complex is too large (155 kD) to pass through the glomeruli. Therefore, the formation of such a complex prevents the body from losing the iron contained in hemoglobin. Determining the content of haptoglobin is of diagnostic value, for example, a decrease in the concentration of haptoglobin in the blood is observed in hemolytic anemia. This is explained by the fact that at T1 / 2 of haptoglobin, which is 5 days, and T1 / 2 of the hemoglobin-haptoglobin complex (about 90 minutes), an increase in the flow of free hemoglobin into the blood during hemolysis of erythrocytes will cause a sharp decrease in the content of free haptoglobin in the blood. Haptoglobin is referred to to acute phase proteins , its content in the blood increases in acute inflammatory diseases.

Enzymodiagnostics - methods for diagnosing diseases, pathological conditions and processes based on determining the activity of enzymes (enzymes) in biological fluids. Enzyme immunoassay diagnostic methods are distinguished into a special group, consisting in the use of antibodies chemically associated with an enzyme to determine in liquids substances that form antigen-antibody complexes with these antibodies. The use of enzyme tests is an important criterion in the recognition of congenital enzymopathies, characterized by specific metabolic and vital disorders due to the absence or deficiency of one or another enzyme. Enzymes are specific high-molecular protein molecules that are biological catalysts, i.e. accelerating chemical reactions in living organisms. The penetration of enzymes from cells into the extracellular fluid, and then into the blood, urine or other biological fluids is an extremely sensitive indicator of damage to plasma membranes or an increase in their permeability (for example, due to hypoxia, hypoglycemia, exposure to certain pharmacological substances, infectious agents, toxins). This circumstance underlies the diagnosis of damage to cells of organs and tissues by the phenomenon of hyperenzymemia accompanying it, and the detected increase in the activity of the enzyme or its isoform may have a different degree of specificity for the damaged organ. The distribution of individual isoenzymes in tissues is more specific for a particular tissue than the total enzymatic activity, so the study of some isoenzymes has become important for the early diagnosis of damage to individual organs and tissues. For example, the determination of the activity of creatine phosphokinase isoenzymes in the blood is widely used for the diagnosis of acute myocardial infarction. , lactate dehydrogenase - for the diagnosis of liver and heart damage, acid phosphatase - and the recognition of prostate cancer. The diagnostic value of enzyme tests is quite high; it depends both on the specificity of this type of hyperfermentemia for certain diseases, and on the degree of sensitivity of the test, i.e. the multiplicity of the increase in enzyme activity in this disease relative to normal values. However, the time of the test is of great importance, because. the appearance and duration of hyperenzymemia after organ damage are different and are determined by the ratio of the rate of entry of the enzyme into the bloodstream and the rate of its inactivation. In certain diseases, the reliability of their diagnosis can be increased by studying not one, but several isoenzymes. So, for example, the reliability of the diagnosis of acute myocardial infarction increases if an increase in the activity of creatine phosphokinase, lactate dehydrogenase and aspartic aminotransferase is noted at certain times. The degree of detected hyperenzymemia objectively reflects the severity and extent of organ damage, which makes it possible to predict the course of the disease.

Human blood plasma contains a huge variety of proteins. They have different functional purpose and molecular structure. These components are characterized by different mobility in a special medium through which an electric current is passed, and in this case an electric field is created. It is on this that the division of the total protein contained in the blood plasma into separate protein fractions is based.

During the analysis of blood plasma, the percentage of individual protein fractions is determined. The thing is that it can change with the development of certain pathologies, including cancer, tuberculosis, and infectious diseases. It is this factor that great importance for the diagnosis of various diseases.

How is the analysis of protein fractions carried out?

Today, the analysis of protein fractions is very popular and is used to clarify the diagnosis in various pathological conditions. It can be prescribed by all specialized doctors. The main indications for the appointment of the study are:

• Inflammatory processes of various etiologies;
• Chronic systemic diseases;
• Diseases that are associated with pathologies in the connective tissue;
• Malignant tumors.

Serum is separated into protein fractions by electrophoresis. In this way, it is possible not only to determine the amount of protein, but also to isolate its individual fractions as a percentage. The separation of protein fractions using the electrophoresis method is based on the different mobility of various proteins under the influence of an electric field.

Preparation for delivery

Blood sampling for the study is carried out from a vein and is always carried out on an empty stomach. At the same time after the last meal at least 12 hours later. During this period, it is allowed to drink only pure water and exclude the consumption of juices, tea and coffee.

In addition, it is important to stop smoking before donating blood and exclude nervous strain. It is not recommended to take blood for analysis after:

• Radiography;
• Fluorography;
• Rectal examination;
• Physiotherapy procedures.

Advice! You should know that any meal, even a small cup of coffee in specified time can significantly distort the results of the study of blood serum.

It is advisable to stop taking medications that reduce the concentration of lipids in the blood a few weeks before conducting blood plasma studies.

In newborns, an analysis of blood plasma for the ratio of protein fractions is carried out in exceptional cases. For example, if a child has observed for three weeks bad dream, poorly erupted teeth or there is a suspicion of the development of rickets.

Advice! It is believed that in newborns, blood sampling from a vein leads to stress that is dangerous for the baby's body, so an analysis for blood serum tests is prescribed only in exceptional cases.

Norms of protein fractions in blood serum

The analysis period is one business day. Five standard protein fractions are isolated by electrophoresis:

• Albumins;
• Alpha-1 globulins;
• Alpha-2 globulins;
• beta globulins;
• Gamma globulins.

If necessary, beta globulins are divided into beta-1 globulin and beta-2 globulin. For an adult in healthy condition the norm of protein in the blood is 62-83 g / l. In children, the amount of protein needed in the blood may vary with age. In newborns, the norm of protein compounds is 48-73 g / l. With age, the normative range gradually changes and is:

• up to 1 year - 47-72 g / l;
• 1-4 years - 61-75 g / l;
• 5-7 years - 52-78 g / l;
• 8-15 years - 58-76 g / l.

The main protein fraction is albumins, their norm is 40-60% of the total amount of protein in the blood. When analyzing the ratio of protein fractions, the following values ​​​​are considered the norm:

The total amount of globulins is almost half of the proteins in the blood. Their rate as a percentage is:

• Alpha-1-globulins - 2-5%;
• Alpha-2 globulins - 7-13%;
• Beta globulins - 8-15%;
• Gamma globulins - 12-22%.

Deviation of results from the norm

In the first place in the analysis of blood serum, the level of albumin in the blood is noted. Its increase may indicate dehydration. This happens, for example, with frequent vomiting or indigestion. Also, an increase in this protein fraction occurs with extensive burns.

But a decrease in the level of the protein fraction is considered more dangerous, which, with a significant deviation from the norm, may indicate:

A slight decrease in albumin can also be observed:

• During pregnancy;
• With an overdose of drugs;
• With a prolonged increase in temperature;
• At smokers.

Due to the large number of possible disorders, the amount of albumin is not of significant diagnostic value, but rather is a reference. More important is the decoding of globulins, the increase and decrease in the level of which, much more accurately indicates specific pathologies.

Deciphering the results of the analysis

These protein fractions are decisive for:

• Protective properties of the body;
• The quality of blood clotting;
• Transfer of vitamins, hormones and other useful components through the tissues of the human body.

It is in this regard that the norm of globulins is important when deciphering the analysis of serum for the percentage of various protein fractions. If a change in the normal amount of alpha-1 globulins is detected during the analysis of blood serum, then this is a very serious sign that may indicate the development of oncological diseases, the presence of infection and inflammatory processes. A decrease in the level of alpha-1 globulins often occurs against the background of:

• Emphysema affecting lung tissue;
• Pathology of the kidneys.

The number of alpha-1 globulins increases with:

• Pregnancy, which is accompanied by pathologies of the fetus;
• Hormonal imbalance;
• Systemic lupus erythematosus.

If the rate of alpha-1 globulins and alpha-2 globulins is reduced, then such a decoding of the analyzes in combination with other studies will confirm the presence of liver pathologies, in particular liver cirrhosis or hepatitis. Besides, low level alpha-2 globulins may be associated with household health problems such as:

• Improper and unbalanced nutrition;
• Disruptions in the work of the intestines.

Indicative for the diagnosis is an increased rate of beta-globulins. First of all, it is a confirming factor for the presence of liver pathologies and the development of malignant tumors. Decreased beta globulins in combination with other studies may confirm:

• Violations in the work of the endocrine system;
• The presence of inflammatory processes in the body;
• Anemia.

Gamma globulins reflect the overall state of the immune system. A significant decrease in their level may indicate AIDS. In addition, a deviation from the norm confirms the presence of allergic reactions and chronic inflammatory processes.

Advice! You should be aware that in young children aged 3-6 months, a temporary decrease in gamma globulins may be observed, which is considered the norm.

Only a specialist can accurately decipher the values ​​\u200b\u200bthat are indicated in the analysis. Moreover, for the diagnosis they are important in the complex. But at the same time general information one can and should know what an increase or decrease in the percentage value of a particular protein fraction indicates. This will prevent the occurrence of a panic mood and help you tune in to the successful treatment of the diagnosed disease.