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Pathogenesis of immune hemolytic anemia
Last reviewed: 23.04.2024
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Autoimmune hemolytic anemia is considered as a kind of "dissymunity" state associated with a thymus-derived deficiency in the population of suppressor cells, a violation of cell cooperation during the immune response, and the appearance of a clone of autoaggressive immunocytes (the proliferation of an "illegal" clone of immunologically competent cells that have lost the ability to recognize their own antigens) . The decrease in the number of T-lymphocytes in the blood is accompanied by an increase in the number of B- and zero-lymphocytes of peripheral blood. The lack of regulatory influence of T cells causes an increased and uncontrolled B-cell immune response, which is associated with an increase in the level of immunoglobulins in the blood serum of patients. Detection of proliferating class on the surface of target cells of immunoglobulins testifies to the autoaggressive nature of the disease. In the implementation of autoimmune aggression, other mechanisms of disturbance of cellular and humoral immunity factors are involved, as evidenced by an increase in lymphocytotoxic and a decrease in the complementary activity of blood serum of patients.
Thermal anti-erythrocyte antibodies (most active at normal body temperature) are in most cases represented by IgG (including different subclasses of IgG1, IgG2, IgG3, IgG4), less often IgA. Cold antibodies (the most active in the cold environment - at a temperature of 4-18 ° C) refer to IgM. Two-phase hemolysins of Donat-Landsteiner, which are revealed in paroxysmal cold hemoglobinuria, are IgG.
The destruction of erythrocytes in autoimmune hemolytic anemia occurs in the spleen or in the spleen and liver simultaneously. In addition, B-lymphocytes of peripheral blood, especially the spleen, are able to interact with their own red blood cells. These lymphocytes carry out a killer function with respect to the old erythrocytes with an average life span that absorbed the maximum number of antibodies.
Three main mechanisms of hemolysis in autoimmune hemolytic anemia are described: phagocytosis with monocytes-macrophages of erythrocytes coated with antibodies and / or complement; lysis of erythrocytes coated with IgG, monocyte-macrophages; complement-mediated lysis.
For the development of hemolysis of erythrocytes that absorbed IgG, the interaction of macrophages of the spleen with a cell coated with antibodies is necessary. The rate of cell destruction depends on the number of antibodies on the cell surface. IgM antibodies cause structural damage to erythrocyte membranes, activate the complement C component; In addition, they cause erythrocyte agglutination.
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