Antibodies - Immunoglobulins: IgG, IgM, Analyzes, Which Mean

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Antibodies - Immunoglobulins: IgG, IgM, Analyzes, Which Mean
Antibodies - Immunoglobulins: IgG, IgM, Analyzes, Which Mean
Video: Antibodies - Immunoglobulins: IgG, IgM, Analyzes, Which Mean
Video: Antibody Testing: IgG and IgM explained 2023, February
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IgG antibodies are proteins that the immune system makes in response to infection. The presence of positive igg antibodies in the body is an indicator of the body's contact with cytomegalovirus, and that the patient himself has normal immunity to this disease.

The content of the article:

  • 1 What does antibodies mean
  • 2 Antibodies as an indicator of the state of the immune system
  • 3 Different classes of antibodies IgG, IgM, IgA
  • 4 When an antibody blood test may be ordered
  • 5 Preparation for the study and blood donation procedure
  • 6 Analysis for antibodies in the diagnosis of TORCH infections
  • 7 Research essence
  • 8 Interpreting Antibody Test Results

    • 8.1 IgA
    • 8.2 IgM
    • 8.3 IgG
    • 8.4 Rh antibodies
    • 8.5 Autoantibodies
  • 9 How much does an antibody test cost
  • 10 Where to get tested for antibodies

What does antibodies mean

Igg antibodies
Igg antibodies

In laboratory diagnostics, it is antibodies that serve as a marker of infection. The general rule for preparing for an antibody test is to donate blood from a vein on an empty stomach (at least four hours should pass after a meal). In a modern laboratory, blood serum is analyzed on an automatic analyzer using appropriate reagents. Sometimes serologic testing for antibodies is the only way to diagnose infectious diseases.

Tests for infections can be qualitative (they give an answer if there is an infection in the blood) and quantitative (they show the level of antibodies in the blood). The rate of antibodies for each infection is different (for some they should not be at all). Typically, reference values ​​(norm indicators) of antibodies can be obtained from the analysis result.

Antibodies as an indicator of the state of the immune system

Antibodies (or immunoglobulins) are special protein molecules. They are produced by B-lymphocytes (plasma cells). Immunoglobulins can either be freely present in the blood or attach to the surface of “defective” cells.

Antibodies were discovered in 1890 by E. Bering and S. Kisato while studying the effect of diphtheria toxin on rabbits. This was the name of the substances that were formed in the blood of rabbits and could not only neutralize the toxin, but also destroy the diphtheria infection.

Having recognized a foreign substance - an antigen, the antibody attaches to it using the so-called protein tail. The latter serves as a kind of signaling flag for specialized immune cells that neutralize "offenders".

There are five classes of immunoglobulins in the human body: IgA, IgD, IgG, IgE, IgM. They differ in weight, composition, and, most importantly, in properties.

IgE and IgD are found in blood serum in small amounts and have no diagnostic value. The most important for the analysis of the state of the immune system and diagnosis are IgM, IgA and IgG.

Igg antibodies
Igg antibodies

IgM is the first immunoglobulin that the body begins to produce in response to infection. It is highly active, stimulates various links of the immune system. It makes up 10% of all immunoglobulin fractions.

About five days after the antigen enters the body, IgG begins to be produced (70-75% of all immunoglobulins). It provides a basic immune response. More than half of all immunoglobulins released during illness belong to this class.

Class G antibodies are so small that they can cross the placenta. It is the antibodies transferred to the child from the mother during pregnancy that protect the newborn in the first months of his life.

IgA is mainly localized in the mucous membranes of the respiratory tract, stomach, intestines and genitourinary system. That is, where pathogens most often enter our body. This class of immunoglobulins, as it were, binds foreign substances and prevents them from attaching to the surface of the mucous membranes. The proportion of IgA is 15–20% of the total amount of immunoglobulins present in the body.

Various classes of antibodies IgG, IgM, IgA

The enzyme-linked immunosorbent assay detects antibodies of infections belonging to various Ig classes (G, A, M). Antibodies to the virus, in the presence of infection, are determined at a very early stage, which ensures effective diagnosis and control of the course of diseases. The most common methods for diagnosing infections are tests for IgM antibodies (acute phase of infection) and IgG antibodies (resistant immunity to infection). These antibodies are determined for most infections.

However, one of the most common tests - hospital screening (tests for HIV, syphilis and hepatitis B and C) does not differentiate the type of antibodies, since the presence of antibodies to the viruses of these infections automatically suggests a chronic course of the disease and is a contraindication, for example, for serious surgical interventions. Therefore, it is important to refute or confirm the diagnosis.

A detailed diagnosis of the type and amount of antibodies in a diagnosed disease can be done by passing an analysis for each specific infection and type of antibodies. Primary infection is detected when a diagnostically significant level of IgM antibodies is detected in a blood sample or a significant increase in the number of IgA or IgG antibodies in paired sera taken with an interval of 1-4 weeks.

Reinfection, or re-infection, is detected by a rapid rise in IgA or IgG antibody levels. IgA antibodies are higher in older patients and more accurately diagnose current infection in adults.

Past infection in the blood is defined as increased IgG antibodies without an increase in their concentration in paired samples taken with an interval of 2 weeks. At the same time, there are no antibodies of the IgM and A classes.

When an antibody blood test may be ordered

Igg antibodies
Igg antibodies

The concentration of antibodies to a particular infection helps to make a diagnosis, determine the level of immunity after vaccination, and reveal hidden diseases. Most often, antibody tests are prescribed for suspected diseases (or to monitor their treatment), such as:

  • measles;
  • hepatitis;
  • chickenpox (chickenpox);
  • rubella;
  • helminthiasis;
  • Helicobacter pylori;
  • giardiasis;
  • Epstein-Barr virus;
  • polio;
  • herpes.

An analysis for immunoglobulins of a certain class can also be prescribed for:

  • sepsis;
  • rheumatoid arthritis;
  • cirrhosis of the liver;
  • oncology;
  • chronic purulent otitis media, meningitis, pneumonia, sinusitis;
  • disruption of the immune system;
  • multiple myeloma;
  • HIV infection.

The study is also relevant for the detection of autoimmune diseases. Such immunoglobulins attach to the cells of the skin, kidneys, liver, blood vessels and mark them as "dangerous" for their own immune system.

If the causes of infertility are identified, an analysis for antibodies to hCG or antisperm antibodies may be prescribed. During pregnancy, a test is carried out for antibodies to the Rh factor.

Preparation for the study and blood donation procedure

Igg antibodies
Igg antibodies

Tests for antibodies to viruses and other infectious agents are carried out exclusively as directed by a doctor.

Blood for antibody tests is taken on an empty stomach. Biomaterial is taken from a vein. Before conducting the study, it is advisable for the patient to avoid emotional overload, do not engage in heavy physical work, do not go to the gym and do not take alcohol.

Antibody analysis in the diagnosis of TORCH infections

The abbreviation TORCH appeared in the 70s of the last century, and consists of capital letters of the Latin names of a group of infections, a distinctive feature of which is that, while being relatively safe for children and adults, TORCH infections during pregnancy are extremely dangerous.

A blood test for TORCH infection is a comprehensive study, it includes 8 tests:

  • determination of antibodies to herpes simplex virus type 1,2 IgM and IgG,
  • determination of antibodies to cytomegalovirus IgM and IgG,
  • determination of antibodies to rubella virus IgM and IgG,
  • determination of antibodies to Toxoplasma gondii IgM and IgG.

Often, infection of a woman with infections of the TORCH complex during pregnancy (the presence of only IgM antibodies in the blood) is an indication for its termination.

Research essence

Igg antibodies
Igg antibodies

Determination of the level of immunoglobulins is carried out using immunofluorescence analysis, or ELISA. A small amount of blood serum and purified antigen are placed on the surface of a special plate. An antigen and an antibody of the same species fit together like a key to a lock and form a special immune complex. After this, a substance is added that stains the immune complex. The concentration of immunoglobulins in the blood serum is determined by the color intensity.

The ELISA method is sensitive even to a small amount of immunoglobulins and has a high specificity. This means that the research results will be reliable and accurate.

Research usually takes 1–2 business days. Some laboratories are ready to issue an urgent result in 2-3 hours, but the cost will be about twice as high.

Deciphering antibody test results

Only a doctor can correctly interpret the results of an immunoglobulin test. It takes into account not only the indicators in the research form, but also the patient's condition, symptoms of the disease or their absence, data from other studies.

Each laboratory uses its own test systems, so the results of analyzes carried out in different diagnostic centers may differ. The boundaries indicated in the article are approximate.

IgA

Igg antibodies
Igg antibodies

Total IgA norms for children:

  • up to 3 months - from 0.01 to 0.34 g / l;
  • from 3 months to 1 year - from 0.08 to 0.91 g / l;
  • from 1 to 12 years old:

    • girls: 0.21 to 2.82 g / l;
    • boys: 0.21 to 2.91 g / l;

For women:

  • 12-60 years old - from 0.65 to 4.21 g / l;
  • After 60 years - from 0.69 to 5.17 g / l.

For men:

  • 12-60 years old - from 0.63 to 4.84 g / l;
  • after 60 years - from 1.01 to 6.45 g / l.

Class A immunoglobulin increases in chronic infections, in cystic fibrosis, and in liver damage. Also, antibodies of this type can be actively produced in autoimmune diseases. A decrease in antibody titer occurs with atopic dermatitis, some diseases of the blood and lymphatic system. And also in violation of the synthesis of protein molecules and taking certain medications.

IgM

The serum IgM content of newborns should be in the range of 0.06-0.21 g / l.

For kids:

  • over 3 months and up to 1 year:

    • girls: 0.17 to 1.50 g / l;
    • boys: 0.17 to 1.43 g / l;
  • from 1 to 12 years old:

    • girls: 0.47 to 2.40 g / l;
    • boys: 0.41 to 1.83 g / l;

For women: 0.33 to 2.93 g / l.

For men: 0.22 to 2.40 g / l.

IgM rises in acute inflammation, pneumonia, sinusitis, bronchitis, bowel and stomach diseases.

If the concentration exceeds the upper limit of the norm, it can indicate liver damage, parasitic diseases, as well as myeloma.

A decrease in IgM levels is observed with violations of protein synthesis or damage to the immune system. This can occur after removal of the spleen, with a large loss of protein, during treatment with cytostatics and other drugs that suppress immunity, with lymphoma, as well as with some congenital conditions.

IgG

Igg antibodies
Igg antibodies

Unlike previous immunoglobulins, IgG levels differ between males and females from birth.

For female representatives, its norms are:

  • up to 1 month - from 3.91 to 17.37 g / l;
  • from 1 month to 1 year - from 2.03 to 9.34 g / l;
  • in 1-2 years - from 4.83 to 12.26 g / l;
  • over 2 years old - from 5.52 to 16.31 g / l.

A strong half of humanity:

  • up to 1 month - from 3.97 to 17.65 g / l;
  • from 1 month to 1 year - from 2.05 to 9.48 g / l;
  • 1-2 years - from 4.75 to 12.10 g / l;
  • over 2 years old - from 5.40 to 16.31 g / l.

IgG can increase in chronic infections, autoimmune diseases, parasitic diseases, sarcoidosis, cystic fibrosis, liver damage, myeloma and granulomatosis.

A decrease in the level of IgG can be observed in oncology of the hematopoietic and lymphatic system, with muscular dystrophy and some other diseases.

In HIV infection, the IgG level can be either extremely high or extremely low, depending on the stage of the disease and the state of the immune system.

Rh antibodies

With antibodies to the Rh factor, everything is a little easier. Normally, they should not be. If antibodies are found, it means that immunization occurred during a previous pregnancy or during a donor blood transfusion.

Autoantibodies

Autoantibodies should also be absent normally. Their presence indicates the development of autoimmune diseases.

How much does an antibody test cost

Igg antibodies
Igg antibodies

There are many types of antibody detection tests. For example, a comprehensive analysis for TORCH infections (toxoplasma, rubella, cytomegalovirus, herpes), which must be taken when planning a pregnancy, will cost 2,000–3,000 rubles. An analysis for antibodies to the Rh factor will cost about 450-600 rubles.

An analysis for antibodies to certain infections costs from 350 to 550 rubles. It should be borne in mind that the determination of, for example, IgG and IgM are two different studies, each of which will need to be paid separately.

Determination of antinuclear (antinuclear) antibodies will cost about 500–750 rubles, antisperm antibodies - 700–1250 rubles, analysis for antibodies to thyroglobulin and thyroperoxidase costs about 400–550 rubles.

It is also necessary to include in expenses about 120-180 rubles for taking blood.

Where can i get tested for antibodies?

A blood test to determine the level of immunoglobulins is performed by many laboratories. But how to choose the one where it will be held simultaneously quickly, efficiently and inexpensively?

When choosing a laboratory, pay attention to the list of analyzes. The larger the list, the more extensive diagnostic capabilities the laboratory has.

Another factor is the time after which you are promised the result. Most laboratories set aside 2-3 days for this study, some provide urgent analysis services - 1 day.

When taking blood, pay attention to the treatment room, its equipment, and consumables used. Everything should be sterile: usually, right in front of you, the nurse wipes the table, pillow, etc. disinfectant. This is a guarantee of your safety.

Another factor is convenience. You don't have to travel across the city to get tested for antibodies for 20-30 rubles cheaper. During the journey, you may experience physical or emotional overload, due to which the results will be distorted.

So, choose a laboratory or medical center with modern medical equipment, a wide range of tests, located near your home or on the way to work or study. If this laboratory has been operating for many years and has managed to gain a certain prestige among doctors and patients, this is an additional plus.

To learn more:

  • ELISA - enzyme-linked immunosorbent assay: transcript
  • Immunoassay blood test in parasitology
  • Antibody blood test: diagnosing the immune system

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