Antibody testing is one of the important diagnostic methods during pregnancy. It allows you to get the result as accurately and quickly as possible and take the necessary measures to protect the baby's health, reduce the risk of complications and serious consequences.

Method of determination Agglutination method + gel filtration (cards). Incubation of standard typed erythrocytes with the test serum and filtration by centrifuging the mixture through a gel impregnated with a polyspecific antiglobilin reagent. Agglutinated erythrocytes are detected on the surface of the gel or in its thickness. The method uses suspensions of erythrocytes from donors of group 0 (1), typed by erythrocyte antigens RH1 (D), RH2 (C), RH8 (Cw), RH3 (E), RH4 (c), RH5 (e), KEL1 (K) , KEL2 (k), FY1 (Fy a) FY2 (Fy b), JK (Jk a), JK2 (Jk b), LU1 (Lu a), LU2 (LU b), LE1 (LE a), LE2 (LE b), MNS1 (M), MNS2 (N), MNS3 (S), MNS4 (s), P1 (P).

Study material Whole Blood (with EDTA)

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Antibodies to the most clinically important erythrocyte antigens, primarily the Rh factor, indicating the body's sensitization to these antigens. Rh antibodies are referred to as alloimmune antibodies.

Alloimmune anti-erythrocyte antibodies (to the Rh factor or other erythrocyte antigens) appear in the blood under special conditions - after transfusion of immunologically incompatible donor blood or during pregnancy, when fetal erythrocytes carrying paternal antigens immunologically foreign to the mother penetrate the placenta into the woman's blood. Non-immune Rh negative people do not have antibodies to the Rh factor.

In the Rh system, 5 main antigens are distinguished, the main (most immunogenic) antigen is D (Rh), which is usually referred to as the Rh factor. In addition to antigens of the Rh system, there are a number of clinically important erythrocyte antigens, to which sensitization can occur, which causes complications during blood transfusion.

The method of screening blood tests for the presence of alloimmune anti-erythrocyte antibodies, used in the Independent Laboratory INVITRO, allows, in addition to antibodies to the Rh factor RH1 (D), to identify alloimmune antibodies to other erythrocyte antigens in the serum under study. The gene encoding the Rh factor D (Rh) is dominant, the gene d allele to it is recessive (Rh-positive people can have the DD or Dd genotype, Rh-negative people can only have the dd genotype).

During the pregnancy of a Rh-negative woman with an Rh-positive fetus, an immunological conflict between the mother and the fetus in the Rh factor may develop. Rh-conflict can lead to miscarriage or the development of hemolytic disease of the fetus and newborns. Therefore, the determination of the blood group, Rh factor, as well as the presence of alloimmune anti-erythrocyte antibodies should be carried out during planning or during pregnancy to identify the likelihood of an immunological conflict between the mother and the child. The occurrence of Rh-conflict and the development of hemolytic disease of newborns is possible if the pregnant woman is Rh-negative, and the fetus is Rh-positive. If the mother has a Rh antigen positive, and the fetus is negative, the conflict on the Rh factor does not develop. The incidence of Rh incompatibility is 1 case per 200 - 250 births.

Hemolytic disease of the fetus and newborns - hemolytic jaundice of newborns, caused by an immunological conflict between the mother and the fetus due to incompatibility of erythrocyte antigens. The disease is caused by the incompatibility of the fetus and the mother for D-Rhesus or ABO (group) antigens, less often there is incompatibility for other Rhesus (C, E, c, d, e) or M-, M-, Kell-, Duffy- , Kidd antigens. Any of these antigens (usually D-Rh antigen), penetrating into the blood of a Rh-negative mother, causes the formation of specific antibodies in her body. The penetration of antigens into the maternal bloodstream is facilitated by infectious factors that increase the permeability of the placenta, minor injuries, hemorrhages and other damage to the placenta. The latter enter the fetal blood through the placenta, where they destroy the corresponding antigen-containing erythrocytes.

Disruption of placental permeability, repeated pregnancies and blood transfusions to a woman without taking into account the Rh factor, etc., predispose to the development of hemolytic disease of newborns. With an early manifestation of the disease, an immunological conflict can cause premature birth or miscarriages. During the first pregnancy with an Rh-positive fetus in a pregnant woman with Rh "-" the risk of developing Rh-conflict is 10-15%. The first meeting of the mother's body with a foreign antigen occurs, the accumulation of antibodies occurs gradually, starting from about 7 to 8 weeks of pregnancy. The risk of incompatibility increases with each subsequent pregnancy with a Rh-positive fetus, regardless of how it ended (artificial abortion, miscarriage or childbirth, surgery for an ectopic pregnancy), with bleeding during the first pregnancy, with manual removal of the placenta, and also if childbirth is carried out by cesarean section or are accompanied by significant blood loss during transfusion of Rh-positive blood (if they were carried out even in childhood).

If a subsequent pregnancy develops with an Rh negative fetus, incompatibility does not develop. All pregnant women with Rh "-" are registered in the antenatal clinic and are dynamically monitored over the level of Rh antibodies. For the first time, an antibody test must be taken from the 8th to the 20th week of pregnancy, then periodically check the antibody titer: once a month until the 30th week of pregnancy, twice a month until the 36th week and once a week until 36th week. Termination of pregnancy less than 6 to 7 weeks old may not result in the mother's Rh antibodies. In this case, during subsequent pregnancy, if the fetus has a positive Rh factor, the likelihood of developing immunological incompatibility will again be 10-15%. Testing for alloimmune anti-erythrocyte antibodies is also important in general preoperative preparation, especially for people who have previously received blood transfusions.

The emergence of an immunological conflict between a mother and a child is due to incompatibility for rhesus or blood group and the production of specific antibodies in the female body.

AB0-incompatibility

Group incompatibility arises when:

• the mother has group I, and the partner has group IV (incompatibility always arises);
• the mother has II, and the father has IV group (the probability of incompatibility is 66%);
• the mother has III, and the father has group IV (probability - 66%);
• the mother has group I, and the father has II or III (the probability of incompatibility is 50%);
• the mother has group II, and the father has III (probability - 50%);
• the mother has group III, and the father has group II (probability - 25%).

In the blood of a woman, isohemagglutinins to erythrocyte antigens of another group are present. The presence of these substances also suggests the occurrence of incompatibility. With other combinations of the AB0 system, incompatibility does not arise for future parents.

Sometimes antibodies appear even before pregnancy. Their production is activated by transfusion of incompatible AB0 (group) blood or donor serum, vaccination. AB0-incompatibility of partners can occur if the history contains data:

• habitual miscarriage;
• undermaturity of pregnancy, its artificial termination at a later date;
• intrauterine fetal death;
• cesarean section and complicated labor (manual separation of the placenta, premature detachment).

Rh incompatibility

Rhesus conflict manifests itself only under the conditions:

• a woman has Rh-negative blood (Rh-);
• the fetus has inherited the Rh + blood of the father.

Important! Rh sensitization occurs more often if partners have compatible or same-group blood.

Since the majority of the population (85%) has Rh +, the likelihood of developing a Rh-related conflict is too small - only 0.8%. However, it is Rh sensitization that is given much attention, since the immunological conflict is fraught with serious consequences for the fetus.

The protein present on the surface of Rh-positive blood erythrocytes is recognized by the woman's immune cells as foreign and triggers the immune fight against it. The woman's immune system, when faced with Rh-positive erythrocytes for the first time, synthesizes specific IgM antibodies. During the first pregnancy, rather large protein formations enter the blood of the fetus only in small quantities, so the probability of immunological incompatibility is only 10%. However, with subsequent pregnancies, the chances of developing Rh incompatibility between the mother and the child increase significantly.

With repeated contact, smaller IgG antibodies are produced, which easily penetrate the placenta into the fetal blood, activating the process of hemolysis (destruction of red blood cells) and the accumulation of bilirubin (a substance resulting from the breakdown of hemoglobin).

Why is blood incompatibility dangerous?

An immune response in the mother destroys the fetus's red blood cells. At the same time, the woman does not suffer in any way, the process of the formation of specific proteins is completely harmless for her and is asymptomatic. Only the fetus experiences the negative effect of the immunological conflict.

The destruction of red blood cells, the main transporters of oxygen to the cells, leads to the accumulation of fluid in all tissues of the fetus. After birth, maternal antibodies in the baby's blood still continue to destroy red blood cells; this process is clinically manifested by hemolytic disease of the newborn (HDN). The condition manifests itself in the following forms:

1. Anemic - the development of anemia of varying severity.
2. Icteric - the appearance of yellowness of the baby's skin due to the accumulation of bilirubin in the blood.
3. Edematous is the most severe and dangerous form, characterized by the accumulation of fluid in the cavities and tissues of the child.

The development of HDN is recorded during an ultrasound examination of the fetus:

• fruit in the "Buddha pose";
• decreased physical activity;
• swelling of the skin of the head and extremities;
• increased intestinal echogenicity;
• the presence of fluid in the abdominal cavity, chest;
• enlarged heart, pericardial effusion;
• placental hyperplasia.

Important! AB0-conflict often gives mild symptoms that do not require serious treatment. Severe forms of Rh incompatibility can result in serious fetal pathology and death.

Determination of antibody titer

Pregnant women with Rh- determine the presence of specific proteins at the initial visit to the gynecologist. Antibody titer is the ratio of serum dilution at which the blood is able to cope with Rh-positive erythrocytes. The amount of antibodies can change (increase / decrease) during pregnancy. The control of the amount of specific proteins is carried out once a month up to 28 weeks, then twice a month and every 7 days after 36 weeks.

It is not possible to predict the development of HDN in group blood incompatibility by the titer of specific proteins.

Failure to detect antibodies in the analysis.

If antibodies are not detected during the first analysis, Rh sensitization can be avoided by the introduction of anti-Rh immunoglobulin. This drug stops the synthesis of antibodies in the maternal body.

Antibodies detected.

In this case, their identification is important. Only the presence of IgG can cause hemolytic abnormalities in the fetus. The degree of risk of developing HDN depends on the indicator:

• a titer of 1: 4 indicates the beginning of the development of an immunological reaction, usually a similar ratio is observed during the first pregnancy;
• titer 1:16 - an indication for amniocentesis (puncture of amniotic fluid and their study to identify intrauterine pathology), in 10% of cases indicates a high risk of intrauterine death;
• a titer of 1:64 or a 4-fold increase in subsequent examination requires early delivery.

The IgG titer in combination with the history data allows 60% to predict the development of HDN, and fetal ultrasound and amniocentesis increase the diagnostic accuracy up to 90%.

The presence of antibodies in the mother does not at all mean the need to abandon pregnancy. Early registration of a pregnant woman, a blood test for antibodies, regular ultrasound of the fetus and vaccination with immunoglobulin will preserve the pregnancy and give birth to a healthy baby in due time.

Pregnancy is an important event in a couple's life. For a woman, it is doubly important, since she has to take care not only of herself, of her partner, but also of the life and health of her unborn child. The sooner she thinks about it, the more chances that gestation (pregnancy) will pass without possible complications, and her baby will be born healthy.

In laboratory medical practice, there are many blood tests that a pregnant woman needs to take - a general blood test, a blood test for human chorionic gonadotropin, a biochemical blood test - but a blood test for antibodies during pregnancy plays perhaps the most important role, since with its help, you can avoid the threat of TORCH infections and Rh-conflict.

Why is blood antibody testing so important?

In the information environment of the modern world, many people come across medical scientific terminology in their everyday life. They are familiar with the words "immunity", "allergy", "antibodies", "immune response", "Rh factor", "Rh-conflict". Often this kind of acquaintance leaves behind the door of understanding the essence of the phenomena hidden behind these words. Below we will try in an accessible form to reveal the main meaning of the concepts sounded above.

Immunity

The immune system is able to resist not only external antigens, it also fights against the "rebellious" cells of the body - cancer cells. And, which is especially important within the framework of our topic, the immune system does not always work adequately and correctly, becoming a threat to the body, and for a woman during gestation - a threat to her fetus.

Inadequate, abnormal functioning of the immune system leads to the emergence of autoimmune diseases, which are also called "allergic". In normal human health, the immune system does not have access to areas of the body such as bone and brain tissue, eyes, embryo, placenta and testes. With the phenomenon of "excessively strong immunity", a situation is possible when the immune system can physically infect the listed objects, overcoming the neutrality of these zones, which is very bad for the health of the human body.

Antibodies

The concept of "antibody" (immunoglobulin) is crucial for understanding the mechanism of the "Rh conflict".

Where do antibodies come from and what are they?

Stem cells are constantly maturing in the red bone marrow. Over time, they turn into red and white blood cells - erythrocytes and leukocytes. Some of the leukocytes (β-lymphocytes) are immediately sent to the lymph nodes and spleen, where they begin to perform their main function - they make antibodies against antigens, and some of the leukocytes enter the thymus, where they become T-lymphocytes (the letter "T" stands for thymus). This is a special form of "advanced" leukocytes, which are very different from their less developed counterparts. So, for example, killer lymphocytes are able to empirically receive information about an antigen, direct it to the thymus (a kind of research center of the body) and carry out targeted elimination of a hostile agent using a long-range attack with cytoxins and flagella in direct contact.

Antibodies appear in the thymus after "intelligence" of T-lymphocytes. The formula for the production of antibodies is directed to stationary β-lymphocytes (plasma cells), which produce them in the future, memorizing the manufacturing method (the principle of permanent immunity is based on this property). After that, antibodies - a powerful weapon against antigens - enter the bloodstream, find the antigen and affect it in the most harmful way.

There are 5 types of antibodies - IgG, IgA, IgM, IgD, IgE, which differ from each other in structure and amino acid composition, as well as in functional purpose. More details in the table:

Rhesus factor

The classical system for determining the blood group is called "AB0", for some reason it is not able to meet the needs of modern medical science, in particular, immunologists who use the alternative Rh system. In total, there are about 40 different approaches to determining blood groups in medicine.

The Rh system is based on a group of 50 antigens, the most important of which are D, C, c, CW, E and e. The terms "Rh positive and negative" refer only to the D antigen (Rh + and Rh-). WHO statistics show that there are only 15% of people on the planet who have Rh negative blood. Antigen D plays an important role in Rh-conflict in blood transfusion (Rh-incompatibility between donor and recipient) and fetal pathology (Rh-incompatibility between father and mother).

The mechanism of the occurrence of Rh-conflict during pregnancy

During the first gestation, the blood of the mother and the fetus does not mix, the D antigen is not detected by the maternal organism, and the Rh conflict does not occur until the moment of delivery, when the immune system inevitably detects the antigen.

The immune system remembers the antigen and forms the memory of it, as it does in the case of the formation of the mechanism of permanent immunity. With repeated gestation, the mother's body begins to react abnormally to pregnancy, as to a disease. In this connection, various autoimmune pathological conditions of the fetus arise: hemolytic anemia with acidosis and hypoxia, thrombocytopenia, dropsy, neutropenia. The threat of TORCH infections (rubella, toxoplasmosis, cytomegalovirus, syphilis, hepatitis-B) is seriously increasing. The mother, against the background of a deterioration in the general condition, may have pleural effusions, powerful toxicosis. The threat of miscarriage, prematurity, preeclampsia increases.

Blood test for antibodies during pregnancy: procedure and interpretation of results

Note that it is better to take tests for antibodies in the blood before the moment of conception of the child. Thus, there will be time for treatment, if necessary, and it will be clear whether the mother's Rh is compatible with the future father of the child.

Preparation for the test procedure

A blood test for antibodies is taken by pregnant women with negative rhesus on a mandatory basis and is performed at 8, 16 and 24 weeks of gestation. An analysis for Rh-conflict is submitted every month until the last month of pregnancy. You must follow a diet before surrendering. You cannot eat before the procedure, and therefore it is necessary to do it in the morning. Blood is taken from a vein.

Decoding the results

On the test form, first of all, attention should be paid to the lgM and lgG antibody indices. They can be indicated approximately using the symbols "+", "-"; words - "negative", "weakly positive" (as an option - "weakly negative"), "positive" and in reference numeric values.

Reference values. Not all laboratories have the same reference limits, and therefore the values ​​that will be given below should be estimated as approximate:

• LgA interval - 0.35-3.55 g / l
• LgG interval - 7.8-18.5 g / l
• LgM interval - 0.8-2.9 g / l

Thus, the lower value, for example, lgM 0.7 will be regarded as lgM-, and the upper one as lgM +. Example (note that in the form, numerical values ​​are combined with the tag "negative", "weakly positive", "positive"):

Symbolic meanings:

• If lgM and lgG are not detected, the test form says "negative", then this means that there are no infections in the body. Nevertheless, the need for laboratory control remains, since it is obvious that the mother's body does not have immunity to diseases.
• lgG + and lgM- will be evidence of a previous infection, this combination does not affect the fetus.
• lgG- and lgM + - the mother contracted the infection during gestation. There is a danger to the fetus.
• lgG + and lgM + - the disease is in an acute stage. There is a threat to the fetus.