Cold agglutinins. Cold agglutinin assay. Immunological test for determining cold agglutinins in hemolytic anemia

KHAB is an autoimmune hemolytic anemia caused by IgM class antibodies, which are cold agglutinins, maximally active at temperatures from 0 to 30 0 C.

With this anemia, the following sequence of events occurs:

AT Ig M binds to the antigen of erythrocytes. Such Ig M-coated erythrocytes are resistant to intravascular lysis, therefore there is no intravascular hemolysis, as with thermal autoimmune anemia, however, such Ig M coated erythrocytes, unlike Ig G coated erythrocytes, are not removed from the bloodstream by macrophages, because macrophages of the spleen and liver do not have receptors for Ig M, therefore, up to a certain stage there is no intracellular hemolysis. When the number of Ig M molecules fixed on the erythrocyte reaches 60, it becomes possible to fix C1 complement. Then C 2 and C4 complement are activated, C1, 2, 4 is formed (C3 - convertase), C3 complement is cleaved, C3b appears, which combines with Ig M and the connection of AT Ig M with C3b occurs.

Such Ig M C3b coated red blood cells are still resistant to intravascular lysis, i.e. There is no intravascular hemolysis, but such red blood cells are already becoming recognizable to macrophages of the liver and spleen, because the latter have receptors for C3b complement and intracellular hemolysis begins. However, a feature of intracellular hemolysis in cold agglutinin disease is that hemolysis occurs mainly in the liver, where red blood cells are quickly phagocytosed, destroyed or released from C3b receptors of macrophages using the C3b inactivator system (C3b inactivator, factor H, etc.), which changes antigenic form C3. Such red blood cells, freed from macrophage receptors, carry Ig M and an altered form of C3 (C3d) on their surface. They are sent into the bloodstream and their lifespan is no different from normal.

Thus, if Ig M anti-erythrocyte antibodies are low (< 60 молекул на клетку) гемолиза нет. Если Ig M антиэритроцитарных антител достаточное количество (>60 molecules per cell), but the C3b inactivator system works effectively, then hemolysis is mild, only a small number of red blood cells are destroyed, and the bulk of them are sent back into circulation. However, if there are a lot of Ig M anti-erythrocyte antibodies, then the C3b inactivator system cannot cope with such a volume, and as a result, only a small number of erythrocytes return to the bloodstream, and the bulk is destroyed, which leads to the clinical picture of intense intracellular hemolysis.

A very large number of Ig M molecules on the surface of the red blood cell leads to another scenario. In this case, the activation of complement is so active that it becomes possible to place both C8 and C9 complement on the erythrocytes, which, unlike C3 and C3b, are capable of causing endovascular lysis of erythrocytes, which also leads to intravascular hemolysis in cold agglutinin disease, although such hemolysis occurs rare and of low intensity.

Current HAB.

The onset is more often acute than with the thermal form. The course is chronic with periodic crises provoked by hypothermia. Local hypothermia (fingers and toes) can provoke intravascular hemolysis, clinically expressed as Raynaud's syndrome or livedo reticularis. The spleen is often not enlarged.

Diagnostics.

As with other forms of AIHA, there are clinical and laboratory signs of anemia. Signs of intracellular (intrahepatic) hemolysis are determined, but there may also be signs of intravascular hemolysis. Attention should be paid to the connection between hemolytic crises and cold.

The direct Coombs test (Coombs gamma test) for CAB is negative, since at t 0 –37 0 the connection between AT Ig M and erythrocyte antigen is weak.

However, it is not the Coombs gamma test with anti-C3 reagent that gives a positive result.

Treatment.

For mild hemolysis, no treatment is required.

Corticosteroids and splenectomy are ineffective.

Transfusions of washed red blood cells are carried out only for health reasons, and it is especially important to warm all intravenous infusions to t 0 37 0.

Plasmapheresis has high efficiency, because allows you to reduce the amount of AT Ig M, because at t 0 37 0 C AT Ig M dissociates from the cell surface and is found mainly in serum.

Immunosuppressive therapy with cytostatics for CAH, as well as thermal AIHA, is effective in 50% of cases.

Intravenous administration of immunoglobulin is most effective for CAB.

Paroxysmal cold hemoglobinuria.

This is the rarest form of autoimmune anemia. It is characterized by the presence of biphasic Donath-Landsteiner hemolysins, belonging to the Ig G class. For anemia to occur, hypothermia of the body is required (cold phase, during which antibodies are fixed on red blood cells), followed by the implementation of extended hemolysis in the thermal phase. Different patients require different degrees of cooling during the first phase of the reaction.

In addition to AT, red blood cells on their surface also fix a large amount of the complement component, which leads to intravascular hemolysis.

The disease is manifested by attacks of chills, nausea, vomiting and the appearance of black urine several hours after hypothermia.

The appearance of antibodies is associated with syphilis and viral infections.

A laboratory test aimed at identifying autoantibodies that cause agglutination and hemolysis of red blood cells during low temperatures.

Synonyms Russian

Cold agglutinins, study of complete cold agglutinins.

English synonyms

Cold agglutinins blood test, Cold Autoantibodies, Cold-Reacting Antibodies.

Research method

Agglutination reaction.

What biomaterial can be used for research?

Venous blood.

How to properly prepare for research?

• Do not smoke for 30 minutes before the test.

General information about the study

Autoimmune hemolytic anemia (AIHA) occurs as a result of a breakdown due to a number of reasons of immunological tolerance and the production of antibodies against one’s own red blood cells. There are warm and cold autoantibodies. Heat ones bind most effectively to erythrocyte antigens at a temperature of 37 °C, and cold ones - at 4-18 °C. Depending on the effect that autoantibodies have on red blood cells in a test tube, hemolysins (destroy cells) and agglutinins (cause red blood cells to stick together) are released.

Autoimmune hemolytic anemia with cold agglutinins - a relatively rare form of immune hemolytic anemia (according to some data, 20% of all cases of AIHA). It can be either idiopathic (the cause is unknown) or symptomatic. The idiopathic variant is more common in elderly and old age(60-80 years), while symptomatic may occur in childhood and adolescence, complicating the course of mycoplasma pneumonia, infectious mononucleosis, legionellosis, as well as systemic autoimmune diseases(systemic lupus erythematosus, rheumatoid arthritis). In older adults, AIHA with cold agglutinins is often associated with lymphoproliferative diseases such as chronic lymphocytic leukemia and Waldenström macroglobulinemia.

Cold agglutinins are most often IgM, less often they are represented by a mixture of immunoglobulins of different classes. They bind to the red blood cell membrane at low temperatures and attach complement, a family of serum proteins that destroy antibody-labeled cells. After the addition of complement, a membrane-damaging complex is formed on the erythrocyte membrane, the formation of which leads to the formation large quantity pores in the cell membrane, its swelling and destruction.

As a laboratory marker of autoimmune hemolysis caused by cold agglutinins, it is advisable to use the detection of antibodies in the patient’s blood serum that lead to agglutination of red blood cells during incubation at low temperatures.

The modern method of testing for cold agglutinins is the gel agglutination reaction. A suspension of donor red blood cells is added to microtubes containing a neutral gel. Then the test serum is added and incubated at a temperature of 2-8 °C. If there are cold agglutinins in the test serum during incubation at low temperatures, they bind to erythrocytes and cause their agglutination. The test result is assessed after centrifugation, during which agglutinated and non-agglutinated red blood cells are separated. Non-agglutinated erythrocytes have a size comparable to the size of gel particles and freely pass through them under the influence of centrifugal force, forming a compact red sediment at the bottom of the microtube, and agglutinated erythrocytes due to large sizes linger on the surface of the gel or in its thickness.

What is the research used for?

• To detect anti-erythrocyte antibodies in the patient’s blood serum that cause hemolysis at low temperatures.

When is the study scheduled?

• If autoimmune hemolytic anemia with cold agglutinins is suspected: characteristic feature diseases - poor tolerance to cold, when the main symptoms appear.

What do the results mean?

Reference values: not detected.

• A negative result - the cells form a compact sediment at the bottom of the microtube - indicates the absence of cold agglutinins in the test serum.
• A positive result - agglutinated cells form a red layer on the surface or in the thickness of the gel - indicates the presence of cold antibodies in the test serum.

What can influence the result?

• In low titers, cold agglutinins can also be detected in healthy people.

Important Notes

• In autoimmune hemolytic anemia with cold agglutinins, autoagglutination of red blood cells occurs at room temperature, which creates problems and leads to incorrect results when determining blood group and calculating peripheral blood parameters (number of red blood cells and red blood cell indices). This agglutination is reversible at 37 °C, so when the blood is heated to body temperature, problems during research are eliminated.

The clinical picture of these diseases combines both characteristic features hemolysis and other manifestations hypersensitivity to cold (poor peripheral circulation). Depending on the predominant production of cold agglutinins or hemolysins, two types are distinguished: clinical forms. Although the development of these conditions is based on common mechanisms, with the help immunological methods their differentiation is possible. Since the corresponding antigen can be detected on the erythrocytes of patients, we're talking about actually about autoimmunization.

Cold agglutinin disease. The picture of the disease caused by cold hemagglutinins was described already in the 19th century. One such case was reported by M. A. Raynaud. The pathogenetic significance of these antibodies was proven only in the 20s of our century. In 1952, Schubothe proposed to distinguish cold agglutinin disease into a special nosology, thereby differentiating it from secondary forms that developed as a result of other pathological processes.

It's relative rare disease mainly affects people over 50 years of age. It accounts for 7.7-10.8% of autoimmune hemolytic diseases and 30-42% of all cases accompanied by the production of cold antibodies.

Symptoms. The patient's complaints generally depend on the nature of the weather. Symptoms appear in the form of hemolysis as a result of the body's increased sensitivity to cold. The patient's condition is complicated when they are combined with the process of cryoprecipitation. Severe hemolytic crises are observed relatively rarely; during these periods, disorders are noted general and hemoglobinuria. Anemia is more severe in the winter months than in the summer. On examination, an enlargement of the spleen is sometimes detected, usually insignificant.

Laboratory data. A standard blood test can reveal signs of a hemagglutination reaction, and partially hemolysis. Agglutinates are especially clearly visible on fixed blood smears. These violations practically exclude the possibility of determining the number of red blood cells in the counting chamber shaped elements blood. Anemia is usually not very severe, but the hemoglobin level may drop to 4 mmol/l. The blood picture mostly shows sphero- and microcytosis, increased reticulocyte content, and polychromatophilic erythrocytes. In preparations prepared after preliminary incubation of a blood sample, phagocytosis of erythrocytes is observed. The content of leukocytes and platelets, as a rule, does not change. Main diagnostic criterion serves as a positive reaction of cold hemagglutinins. Due to the binding of antibodies to red blood cells, it is necessary to centrifuge the blood and separate the serum at 37 °C. Considering special properties these antibodies, the study is carried out at different temperature conditions: 10, 20, 30 and 37°C. In contrast to the norm, titers of cold antibodies at 4°C exceed 1:500. Both titer and temperature amplitude of detected antibodies are important for differential diagnosis. Positive direct AHT is mainly the result of sensitization of red blood cells by complement components. The activity of the latter is often reduced.

Current. The disease is characterized by a chronic course and is difficult to treat. Sometimes symptoms persist for 10 years or more; organ tumors are often found in such patients immune system. Reasons fatal outcome there may be infections, anemia, complications after blood transfusion, or, finally, progression of the underlying disease. Spontaneous remissions are quite rare.

Diagnostics . The diagnosis of the idiopathic form of cold agglutinin disease is made based on the detection of cold antibodies (titer more than 1:500, temperature above 15 ° C). For cold hemoglobinuria, the activity of Donath-Landsteiner antibodies is determined. From the point of view of differential diagnosis, cases of Waldenström's macroglobulinemia are interesting. Some authors consider cold agglutinin disease as special shape this disease or plasmacytoma.

Etiology. Monoclonal proliferations of the B-cell type are primarily cited as the causes of the development of primary forms. The concentration of autoantibodies may increase during the development of lymphoma, chronic lymphocytic leukemia, and less commonly lymphogranulomatosis, but during the transition to malignant form autoantibodies are not detected.

Secondary forms of autoimmune hemolytic anemia caused by cold antibodies, as a rule, are acute or subacute in nature. They are relatively rare. Much more often, a subclinical course of the disease and positive AHT are observed (in 60-80% of cases with infections caused by mycoplasma or infectious mononucleosis). Symptoms usually appear 10-20 days after the onset of acute infection, which often coincides with the convalescence stage. At infectious mononucleosis they are registered already at the beginning of the disease: in such patients, as a rule, there is a reduced level of antibodies (compared to the chronic form), as well as less pronounced Clinical signs. Most often, a hemolytic crisis is observed, accompanied by general weakness, pallor and icterus skin.

Laboratory findings are generally consistent with those for idiopathic AIHA. The antibody titer ranges from 1:512 to 1:32,000 (at 2-4°C), the temperature amplitude is reduced. If the underlying disease is acute infection, then the forecast secondary violations quite favorable. With a gradual decrease in the level of cold agglutinins, the patient’s clinical condition normalizes. For viral infections, the criterion for differential diagnosis is hemolysis due to the activity of warm antibodies.

Serological data. The phenomenon of cold hemagglutination was first described by K. Landsteiner in 1903. He identified specific antibodies as follows: first, I removed erythrocyte aggregates formed with the help of cold hemagglutinins from the serum, placed them in an isotonic NaCl solution, and then, by increasing the temperature of the medium, achieved the separation of bound antibodies.

Specificity of cold antibodies. In contrast to warm autoantibodies, cold hemagglutinins have been demonstrated to have no specificity for any particular antigen, although they react unequally with red blood cells different types animals. Thus, antibody reactions with rabbit erythrocytes have been described, guinea pig, chicken, sheep, cat, pig, mouse and monkey, which led to their name “panagglutinins”. The most significant, “strong” antigen was discovered by A. S. Wiener et al. when examining a patient with an extremely high titer of cold agglutinins. The antibodies under study did not react with the patient's red blood cells, but agglutinated the red blood cells of almost all other individuals. The agglutinogen was designated I antigen to reflect the special properties of red blood cells reacting with the corresponding anti-1 serum; the absence of this agglutinogen is indicated by the symbol i. 1-antigen is closely related to the AB0 system. By chemical structure it is probably a polysaccharide. Newborns have exclusively phenotype i. In the 3rd week of the postnatal period, the synthesis of the I-antigen increases, as a result, in a child over 18 months of age, phenotype I is determined, and the i-antigen is practically lost. Meanwhile, it has been suggested that erythrocytes may carry residual structures of the i-antigen. Detailed studies have shown that the IF antigen is present in equal quantities on both umbilical cord blood and adult red blood cells, and the 1° antigen is synthesized from i. Phenotype i is found in adults with a frequency of 1:4000 - 1:5000, the probability of positive reactions increases significantly with leukemia. Since the switching of synthesis from i to I occurs after birth, this can explain the fact that anti-I agglutinins in a low titer (up to 1:64) and with a small temperature amplitude (up to 22°C) are determined in healthy individuals. It is believed that these antibodies are a sign of the normal process of sensitization; they are polyclonal in nature, in contrast to the monoclonal cold agglutinins characteristic of the disease.

As a rule, the antigen that reacts with cold autoantibodies is not identical to the antigen to natural antibodies. Within the group of cold autoAbs, different specificities were also identified; for 90% of them, an epitope was found on a 1-molecule.

Anti-i cold agglutinins have been described in infectious mononucleosis, liver cirrhosis, malignant reticulosis, and tropical splenomegaly. These antibodies are also heterogeneous (four types of specificity have been identified). Since the antigen responsible for the production of anti-1 antibodies is usually absent, the pathogenetic significance of the latter is low. IN last years There have been reports of the Pr antigen, which is found on the erythrocytes of adults and fetuses. Unlike antigens I and i, it is inactivated by proteases.

Within this group, the following antigens are distinguished:

Determined by N-acetylneuraminic acid (inactivation by neuraminidase);

Neuraminidase-resistant.

Differential diagnosis requires analysis using both native and protease-treated red blood cells.

Antibody classes. Unlike heat antibodies, we are talking mainly about antibodies IgM class. The specificities of anti-Pr and anti-i are often referred to as other classes of Ig. Cold antibodies of the IgG class have been detected in the Melanesian population. Cold agglutinins of the IgA class, predominantly of Pr-specificity, have been identified in lymphoproliferative diseases and liver cirrhosis. Due to the inability to activate complement, patients have no hemolytic manifestations, while acrocyanosis is significantly pronounced.

In the chronic form of cold agglutinin disease, as in Waldenström's disease, the electropherogram shows a monoclonal peak. The lg composition is represented exclusively by x-chains. Based on these data, it was suggested that the idiopathic variant of cold agglutinin disease should be considered as a special form of Waldenström's macroglobulinemia. Significant heterogeneity of cold agglutinins was proven in the study of sera from patients with infections; in these cases, the antibodies consisted of two types of L chains. B-lymphocytes of peripheral blood also have the ability to cold agglutination (the phenomenon of rosette formation with erythrocytes).

Hemagglutinin titers depend on the pH and temperature of the medium. Usually they weakly correlate with the clinical status of the patient, however, at the optimal temperature the level of antibodies is quite high - from 1:8000 to 1:64000, sometimes reaching a maximum of 1:168,000,000. Significant antibody titers have been described at chronic forms, medium - for acute and subacute course diseases. It is noteworthy that in in rare cases Antibodies are found in low titers and in practically healthy individuals.

Temperature dependence. The pathogenic effect of cold antibodies depends directly on the temperature amplitude. It turned out that at a high titer and a temperature of about 15 ° C, antibodies are less active than at a low titer and at 32 ° C or more. While high temperatures can support a chronic hemolytic process, low temperatures tend to induce a crisis. Detailed studies have shown that upper limit temperature amplitude is determined by the enhanced dissociation of antibodies initially fixed on the surface of erythrocytes. There is an inversely proportional relationship between the process of antibody formation and temperature amplitude. This equally applies to the relationship between antibody titer and temperature. The optimal temperature for antibody binding on red blood cells ranges from 1 to 4 C, and in healthy individuals it rarely exceeds 15 ° C. In acute and subacute secondary forms, this indicator generally corresponds to 20-25 ° C, with chronic course may reach 32°C or more. The special ability to bind antibodies under cold conditions is probably determined by the properties of the erythrocyte membrane, or rather the antigen-bearing molecules of glycophorin, since this dependence on temperature is not observed when binding to an isolated I-antigen. Antibodies of type anti-I rarely exhibit cryoprecipitin activity; anti-i antibodies more often have this quality. Dissociation of antibodies at more high temperature after binding, the C3 component of complement can serve as evidence of the presence of receptors for C3.

“Monothermic cold agglutinins” are sometimes called antibodies that cause hemolysis in acidified serum, for example, at 20 ° C. Their activity manifests itself at a significant amplitude when summed up temperature conditions binding (0-30 °C) and lysis (15-40 °C).

Complement fixation has pathogenetic significance. By participating in the antigen-antibody reaction, this process can lead directly to hemolysis and also cause a number of sublytic changes. Hemolysis itself occurs under the condition of general activation of complement. The correlation between the titers of cold agglutinins and cold hemolysins is relatively weak. The optimal temperature at which the hemolytic effect is observed is approximately 20 ° C, which suggests a state of hypothermia. The temperature rarely exceeds 32°C. Severe cooling in such patients can lead to paroxysmal hemoglobinuria.

Sublytic complement fixation is limited to component C3. With the help of the C3b inactivator, C3a is cleaved from C3b, so that, as a rule, only C3d remains bound. The process of binding complement components also occurs if, as a result of heating, antibodies are separated from the cell surface. The presence of C3d prevents the fixation of antibodies (blockade of I-determinants), as well as further activation of complement (blockade of binding sites for C3b).

The reasons that determine either sublytic fixation of complement or complete hemolysis are not yet entirely clear. It is assumed that in the first case we are talking about special resistance of erythrocytes. The study of the process of binding complement components made it possible to explain the phenomenon of incomplete antibodies from a different perspective; if erythrocytes are incubated with serum containing cold hemagglutinins, then after heating to 37 ° C (antibody separation) and subsequent washing they do not agglutinate with antiglobulin serum. Previously, it was believed that incomplete antibodies, i.e., incapable of agglutination, bind to the surface of erythrocytes, but in experiments using monospecific anti-Ig sera, neither IgM, nor IgG or IgA were detected.

Cold agglutinins have pathogenetic significance in a number of cases. clinical conditions. Along with this, they are detected in the absence of symptoms of the underlying disease.

Etiology. Most probable cause The appearance of hemagglutinins in immunoproliferative diseases is caused by abnormal synthesis of antibodies. Unfortunately, the pathogenesis of most secondary forms has not yet been studied. The fact that anti-I sera are particularly reactive with rabbit erythrocytes suggests that an exogenous cross-reacting antigen similar to the rabbit antigen is responsible for antibody production. In this regard, it is of interest to observe that anti-I serum is involved in positive reaction with sheep erythrocytes, however, the search for these heterospecific cross-reacting antigens has so far been unsuccessful. The exception is the reaction with mycoplasmas. It has been established that sensitization of rabbits with human erythrocytes treated with mycoplasma leads to the production of high titers of anti-I antibodies. It follows from this that the immune response is associated with the interaction of mycoplasma and erythrocytes carrying a common antigen. In young mice of the NZB/B1 line, IgM antibodies to antigen I are regularly detected, which is apparently associated with the development of lymphoid tissue tumors in animals.

Pathogenesis. Cooling the blood to the temperature of activity of the corresponding antibodies leads to the binding of Ig and the first C-components on the surface of erythrocytes. When reheated, the antibodies are separated, and the process of complement activation can, on the contrary, intensify (subject to certain conditions, up to C9). The timing and severity of antibody formation are determined by the temperature amplitude. The main symptoms are associated with the development of a hemolytic crisis. It has been shown that among the active factors limiting hemolysis, important role plays a C3b inactivator. The consumption of antibodies is of less importance, since after separation elevated temperature they can completely retain their properties. In general, hemolytic manifestations depend on the following factors:

Temperature amplitude optimal for the activity of cold hemagglutinins;

Binding of complement components and their lytic properties;

Degree of sensitivity or resistance of red blood cells;

Activity of the monocyte-macrophage system (extravascular hemolysis).

Treatment . In hemolytic crises there is no need for special treatment, the therapy provided is usually related to the underlying disease. Splenectomy was effective only in some cases. The clinical effect was especially pronounced when 51Cr-labeled red blood cells were localized predominantly in the spleen rather than in the liver. Penicillamine was recommended on the basis of the idea that by cleaving IgM molecules it could thereby inactivate antibodies, but this was not subsequently confirmed. Therapeutic effect cytostatics (for example, cyclophosphamide or chlorambucil) have been described only in isolated cases in patients with immunoproliferative processes. Because of the possible side effects It is preferable to use these drugs only during an exacerbation. Blood transfusions are usually prescribed if necessary emergency care(blood sample should be warmed to 37°C). Some success has been achieved using plasmapheresis (at 37°C). Corticosteroids were virtually ineffective.

Pay attention to limited opportunities therapy, important prevention requirements should be observed: to prevent hypothermia of the body.

Normal red blood cells are quite resistant to the hemolytic action of complement due to special protective mechanisms, therefore severe hemolysis with hemoglobinuria occurs only when a large number of antibodies are activated, for example during sudden hypothermia. Activation of complement is always accompanied by fixation on erythrocytes of C3dg (a cleavage product of the C3 component), which is detected using the appropriate antiserum using a direct Coombs test in all patients with severe hemolytic anemia with cold antibodies. Skin manifestations of this disease, as well as hemolysis, subside with increasing ambient temperature.

Cold agglutinins are more often IgM, less often a mixture of immunoglobulins of different classes, which cause maximum agglutination of erythrocytes at 4 degrees C. Cold agglutinins appear in some diseases, for example, mycoplasma pneumonia, less often with influenza, adenoviral infection and other acute respiratory infections, as well as with sleep diseases. The detection of cold agglutinins in a titer of 1/32 or a fourfold increase in their titer within 7-14 days is considered diagnostically significant.

Cold agglutinins are active at temperatures below 37*C; they bind antigen most effectively at 4*C. When blood enters areas of the body whose temperature is below 37*C, cold agglutinins are fixed on the surface of red blood cells and bind complement, which causes hemolysis (the skin temperature of the extremities can normally drop to 30*C). The intensity of hemolysis depends on the temperature at which cold agglutinins are active.

Cold agglutinins, which react with antigens over a wide temperature range, remain associated with erythrocytes even when blood returns to the great vessels, where higher temperatures enhance complement fixation. Cold agglutinins, which are active in a narrow temperature range, are separated from red blood cells when blood returns to the great vessels. They are more typical for viral infections and mycoplasma pneumonia.

Types of cold agglutinins:

In very rare cases, cold antibodies belong to the IgG class (biphasic Donath-Landsteiner hemolysins in paroxysmal cold hemoglobinuria).

Cold agglutinins in low titer (no more than 1:64) can be detected in healthy people. They are usually polyclonal and directed against the I antigen of erythrocytes.

Cold antibodies react with antigen at 4*C.

Cold antibodies appear in two cases:

Sometimes cold antibodies are found in other neoplasms.

The transient appearance of cold antibodies is characteristic of two infections:

In both cases, the antibody titer is usually so low that clinical manifestations of hemolytic anemia are absent. Only in isolated cases is hemolysis observed. However, the presence of antibodies has diagnostic value.

Cold antibodies are sometimes found in other viral infections, but their appearance usually does not lead to serious consequences.

The specificity of antibodies can help in diagnosing the underlying disease.

Cold antibodies that react preferentially with adult red blood cells rather than fetal red blood cells are called anti-I antibodies (see "Blood transfusion"). They are typical for

Blood diseases

Cold agglutinins

Cold agglutinins, or cryoproteins, are antibodies that interact with red blood cell membrane antigens. This may activate the complement system, causing autoimmune reaction, leading to aggregation and destruction of red blood cells, but only at low temperatures. This pathology occurs mainly in patients over 50 years of age. Antibodies can be represented by IgM, IgG or IgA; in the first case, agglutination is significantly expressed. There are laboratory methods for diagnosing cold agglutinins and determining the temperature at which agglutination begins. Usually the cause of cold agglutinins is an infection, most often viral. Their number may gradually decrease, so if they are detected, surgery under conditions of hypothermia and using cold cardioplegia is best postponed if possible. You can also determine the titers of cold agglutinins when different temperatures blood, and when perfusing, avoid cooling to a temperature at which agglutination may occur. If, however, deeper hypothermia is still necessary, plasmapheresis is required to remove the antibodies contained in the serum. With high titers of cold agglutinins, cooling can lead to serious complications: perioperative myocardial infarction, renal failure, hemolytic anemia, thrombosis. Planning of surgery in such patients should be especially careful, aimed at avoiding cooling the patient. Hemodilution during CPB reduces the risk of agglutination to some extent, but this effect is not predictable enough, so the patient should not be cooled before, during, or after CPB. It is advisable to use a heated water mattress; IR should be performed at normothermia, preheating the solution filling the system. If red blood cells are administered during CPB, they must also be prewarmed. If cold cardioplegia is necessary, it should be crystalloid, not containing blood. In this case, they begin with the introduction of 200 - 300 ml warm solution, which flushes blood out of the coronary arteries, then a cold solution is injected. The temperature of a cold cardioplegic solution is such that it will almost certainly lead to agglutination, so cardioplegia containing blood is administered only warm. Immediately before removing the clamp from the aorta, it is advisable to inject a warm cardioplegic solution so that the blood entering coronary arteries, did not cool.

Sickle cell anemia

Normally, human erythrocytes contain mainly hemoglobin A, sickle cell anemia is caused by the content of abnormal hemoglobin S in erythrocytes. In patients homozygous for this trait, erythrocytes contain predominantly hemoglobin S, clinically this is manifested by sickle cell anemia. In heterozygous patients, hemoglobin S is less than 45% of the total; they are carriers of the disease gene. In sickle cell anemia, red blood cells have a characteristic sickle or crescent shape, are less mobile, tend to aggregate, and are destroyed more quickly. When oxygen levels are low, sickled red blood cells may precipitate. In patients with sickle cell anemia, in addition to anemia itself, intravascular thrombosis is noted. During a crisis (or crisis - I’m not sure, I don’t remember) occlusion occurs blood vessels accompanied by pain, shortness of breath and convulsions.

Perfusion tactics should be aimed at avoiding a crisis with all its consequences. Needs to be supported high level oxygen saturation and do not cool the patient. In patients with a predominant content of hemoglobin S, the oxygen saturation of erythrocytes should be at least 85%, in patients with a partial content of hemoglobin S - at least 40%. In patients with partial hemoglobin S levels, during CPB it is necessary to maintain a high level of oxygen saturation and avoid acidosis, which contributes to the destruction of sickled red blood cells. By following these rules, complications can usually be avoided. Cooling also contributes to sickle cell dysfunction, so it is best to avoid cooling and use warm or crystalloid cardioplegia in the same way as for cold agglutinins. Hemodilution during perfusion also plays a positive role. In order to prevent vascular obstruction, vasodilators should be used.