Immune hemolytic anemia associated with thermal antibodies
Last reviewed: 23.04.2024
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Symptoms of immune hemolytic anemia associated with thermal antibodies are the same in both idiopathic and symptomatic forms. According to the clinical course are divided into 2 groups. The first group is represented by an acute transient type of anemia, which is predominantly noted in young children and often appears after an infection, usually a 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, the appearance of pallor of the skin, icterism, abdominal pain and lower back, hemoglobinuria. In this group of patients, no major systemic diseases are observed. Characteristic features for the acute form of autoimmune hemolytic anemia are the invariable response to corticosteroid therapy, low lethality and complete recovery within 2-3 months after the onset of the disease. This form of autoimmune hemolytic anemia is caused by thermal hemolysins.
In the second type there is a prolonged chronic course with a leading clinical syndrome of jaundice and splenomegaly. Signs of hemolysis persist for many months or even years. Often, violations from other blood elements are detected. The response to corticosteroid therapy is expressed in varying degrees and is not necessary. Lethality is 10% and is often associated with the course of the underlying systemic disease. This form of autoimmune hemolytic anemia is associated with thermal agglutinins.
Laboratory data
For autoimmune hemolytic anemia with thermal antibodies, severe anemia is characteristic, in which hemoglobin decreases to below 60 g / l. In the peripheral blood, spherocytes are found, which are formed as a result of the action of macrophages of the spleen on the membrane of red blood cells coated with antibodies. There is a reticulocytosis, sometimes there are normocytes (nucleated cells). In some cases, the initially low level of reticulocytes indicates the severity of the process in which the bone marrow has simply not had time to respond to it, or the antibodies are also directed against the reticulocytes (rarely) and / or patients may have a concomitant deficiency of folic acid or iron. Often there is leukocytosis with a shift of neutrophils to myelocytes, less often there is leukopenia. The number of platelets either does not change, or thrombocytopenia is observed. In a number of cases, the development of immune pancytopenia is possible. The level of haptoglobin decreases; when the intravascular component of hemolysis is expressed, the level of plasma hemoglobin increases.
Decisive in diagnosis are the results of direct Coombs test, based on the detection of antibodies fixed on the patient's erythrocyte membrane. Positive direct Coombs test is observed in 70-80% of cases of autoimmune hemolytic anemia with thermal agglutinins. The activity of these antibodies is manifested at a temperature of 37 ° C ("thermal" agglutinins); they belong to the class IgG. To display their activity, complement is not required, but subclasses of IgG-IgG1 and IgG3 can activate complement; sometimes complement (C3d) is also found on the erythrocyte membrane. The Coombs test with hemolysin forms of autoimmune hemolytic anemia is often negative. A negative Coombs test may be associated with a small amount of antibodies on the cell surface (for a positive reaction on the surface of the erythrocyte membrane there must be at least 250-500 IgG molecules) both in mild disease and in acute exacerbation, when many hemolytic crises are destroyed erythrocytes. Currently, immunoenzyme and radioimmunoassay methods have been developed that allow quantitative determination of anti-erythrocytic autoantibodies and are the main method in the diagnosis of Coombs-negative autoimmune hemolytic anemia. The use of anti-Ig and antikomplementary antisera allows the determination of the presence on the surface of erythrocytes of various classes and types of Ig-components of complement. The ELISA method allows to monitor the level of antibodies during treatment.
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