Immune hemolytic anemias

Immune hemolytic anemias are a heterogeneous group of diseases in which blood or bone marrow cells are destroyed by antibodies or sensitized lymphocytes directed against their own unmodified antigens.

Depending on the nature of the antibodies, there are 4 types of immune hemolytic anemia: alloimmune (isoimmune), transimmune, heteroimmune (haptenic), and autoimmune.

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Isoimmune hemolytic anemias

They are observed in cases of antigenic incompatibility of the genes of the mother and fetus (hemolytic disease of the newborn) or when erythrocytes incompatible in terms of group antigens enter the body (transfusion of incompatible blood), which leads to a reaction of the donor's serum with the recipient's erythrocytes.

Hemolytic disease of the newborn is most often associated with incompatibility of the mother's and fetus's blood by the RhD antigen, less often by the A B O antigens, and even less often by the C, C, Kell and other antigens. Antibodies penetrating the placenta are fixed on the fetus's erythrocytes and then eliminated by macrophages. Intracellular hemolysis develops with the formation of indirect bilirubin, toxic to the central nervous system, with compensatory ernthroblastosis, and the formation of extramedullary foci of hematopoiesis.

Transimmune hemolytic anemia

Caused by transplacental transfer of antibodies from mothers suffering from autoimmune hemolytic anemias; antibodies are directed against a common red blood cell antigen of both mother and child. Transimmune hemolytic anemia in newborns requires systematic treatment, taking into account the half-life of maternal antibodies (IgG) of 28 days. The use of glucocorticoids is not indicated.

Heteroimmune hemolytic anemia

Associated with fixation of a hapten of medicinal, viral, bacterial origin on the surface of an erythrocyte. An erythrocyte is a random target cell on which a hapten-antibody reaction occurs (the body produces antibodies against "foreign" antigens). In 20% of cases, the role of drugs can be revealed in immune hemolysis.

Autoimmune hemolytic anemias

In this type of hemolytic anemia, the patient's body produces antibodies directed against its own unmodified red blood cell antigens. They occur at any age.

Types of immune hemolytic anemia

Autoimmune hemolytic anemia is considered as a specific state of "dysimmunity" associated with a deficiency of the thymus-derived population of suppressor cells, disruption of cell cooperation during the immune response, and the emergence of a clone of autoaggressive immunocytes (proliferation of an "illegal" clone of immunologically competent cells that have lost the ability to recognize their own antigens). A decrease in the number of T-lymphocytes in the blood is accompanied by an increase in the number of B- and zero lymphocytes in the peripheral blood.

Pathogenesis of immune hemolytic anemias

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Autoimmune hemolytic anemias associated with warm antibodies

Clinical manifestations of the disease are the same in both idiopathic and symptomatic forms. According to the clinical course, they are divided into 2 groups. The first group is represented by an acute transient type of anemia, which is mainly observed in young children and often appears after an infection, usually of the respiratory tract. Clinically, this form is characterized by signs of intravascular hemolysis. The onset of the disease is acute, accompanied by fever, vomiting, weakness, dizziness, pale skin, jaundice, abdominal and lower back pain, hemoglobinuria. This group of patients does not have any major systemic diseases.

Warm antibody-associated immune hemolytic anemias

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Autoimmune hemolytic anemias associated with "Cold" antibodies

Red blood cell antibodies that become more active at low body temperatures are called "Cold" antibodies. These antibodies belong to the IgM class, and complement is required for their activity to manifest. IgM activates complement in the extremities (hands, feet), where the temperature is lower than in other parts of the body; the complement cascade is interrupted when red blood cells move to warmer areas of the body. Natural cold agglutinins in low titers (1:1, 1:8, 1:64) are found in 95% of healthy people.

Autoimmune hemolytic anemias associated with "Cold" antibodies

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Autoimmune hemolytic anemias with incomplete warm agglutinins

Autoimmune hemolytic anemia with incomplete warm agglutinins is the most common form in adults and children, although in the latter, according to some data, paroxysmal cold hemoglobinuria is no less common, but is less frequently diagnosed. In children, autoimmune hemolytic anemia with incomplete warm agglutinins is most often idiopathic, immunodeficiency syndromes and SLE are the most common causes of secondary autoimmune hemolytic anemia. In adults, this form of autoimmune hemolytic anemia often accompanies other autoimmune syndromes, CLL and lymphomas.

Autoimmune hemolytic anemias with incomplete warm agglutinins

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Autoimmune hemolytic anemia with complete cold agglutinins

Autoimmune hemolytic anemia with complete cold agglutinins (cold agglutinin disease) in children occurs much less frequently than other forms. In adults, this disease is often detected: this form is either secondary to lymphoproliferative syndromes, hepatitis C, infectious mononucleosis, or idiopathic. In the idiopathic form of anemia, however, the presence of clonal expansion of the population of morphologically normal lymphocytes producing monoclonal IgM is also shown.

Autoimmune hemolytic anemia with complete cold agglutinins

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