Immune hemolytic anemias associated with heat antibodies

Symptoms of immune hemolytic anemias associated with warm antibodies are the same for 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. Characteristic features of the acute form of autoimmune hemolytic anemia are an invariable response to corticosteroid therapy, low mortality and complete recovery within 2-3 months after the onset of the disease. This form of autoimmune hemolytic anemia is caused by warm hemolysins.

The second type is characterized by a long-term chronic course with the leading clinical syndrome of jaundice and splenomegaly. Signs of hemolysis persist for many months or even years. Disturbances in other blood cells are often detected. The response to corticosteroid therapy is expressed to varying degrees and is not obligatory. Mortality is 10% and is often associated with the course of the underlying systemic disease. This form of autoimmune hemolytic anemia is associated with warm agglutinins.

Laboratory data

Autoimmune hemolytic anemia with warm antibodies is characterized by severe anemia, in which hemoglobin decreases to a level below 60 g/l. Spherocytes are found in the peripheral blood, which are formed as a result of the action of splenic macrophages on the membrane of erythrocytes coated with antibodies. Reticulocytosis is noted, sometimes normocytes (nucleated cells) appear. In some cases, the initially low level of reticulocytes indicates the severity of the process, in which the bone marrow simply has not yet had time to react to it or the antibodies are also directed against reticulocytes (rare) and / or patients may have concomitant deficiency of folic acid or iron. Leukocytosis with a shift of neutrophils to myelocytes is often noted, leukopenia is detected less often. The number of platelets either does not change, or thrombocytopenia is observed. In some cases, immune pancytopenia may develop. The level of haptoglobin decreases; with a pronounced intravascular component of hemolysis, the level of plasma hemoglobin increases.

The results of the direct Coombs test, based on the detection of antibodies fixed on the membrane of the patient's erythrocytes, are decisive in diagnosis. A positive direct Coombs test is observed in 70-80% of cases of autoimmune hemolytic anemia with warm agglutinins. The activity of these antibodies appears at a temperature of 37 0C ("warm" agglutinins); they belong to the IgG class. The presence of complement is not required for their activity to manifest, but the IgG subclasses - IgG1 and IgG3 can activate complement; sometimes complement (C3d) is also detected on the membrane of erythrocytes. The Coombs test is often negative in hemolysin forms of autoimmune hemolytic anemia. A negative Coombs test may be associated with a small number of antibodies on the cell surface (for a positive reaction, at least 250-500 IgG molecules must be present on the surface of the erythrocyte membrane) both in a mild course of the disease and in a sharp exacerbation, when many erythrocytes are destroyed after a hemolytic crisis. Currently, enzyme immunoassay and radioimmunological methods have been developed that allow quantitative determination of anti-erythrocyte autoantibodies and are the main method in the diagnosis of Coombs-negative autoimmune hemolytic anemia. The use of anti-Ig and anti-complementary antisera allows determining the presence of various classes and types of Ig components of complement on the surface of erythrocytes. The ELISA method allows monitoring the level of antibodies during treatment.

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