Autoimmune Hemolytic Anemia Predominantly Associated with IgA Anti-E and Anti-c

Abstract

A patient with warm autoimmune hemolytic anemia (AIHA) due to predominance of immunoglobulin A (IgA) with an Rh specificity, considered to be the first case in Korea, is described. A 13-year-old male patient with severe hemolytic anemia showed a weak reactivity (1+) in the direct antiglobulin test (DAT) by using anti-IgG antiglobulin reagent. This finding, however, could not fully explain the patient's severe AIHA. When anti-IgA reagent was used for the DAT, strong reactivity (4+) was observed and free anti-E and anti-c autoantibodies were also detected by anti-IgA and anti-IgG reagents. The patient's hemoglobin began to rise with the administration of steroids. Because RBCs coated with multiple types of immunoglobulins are associated with more severe hemolysis than those only with IgG, the DATs using anti-IgA and other reagents are needed for the correct diagnosis when the result of DAT is not compatible with patient's clinical manifestations.

IgA-mediated human autoimmune hemolytic anemia as a result of hemagglutination in the spleen, but independent of complement activation and FcαRI

“…3 However, wAIHA associated exclusively with IgA antibodies, reacting optimally at 37°C, remains rare. 1,[4][5][6][7][8] Some of the features of these reported cases, including disease severity, high binding potency of IgA for RBCs with very little free antibody detectable in the serum, no strong evidence of blood group specificity, and in some cases, refractoriness to first-line treatment (administration of high doses of glucocorticosteroids), seem to be characteristic. 1 IgA antibodies exist in several forms, monomeric IgA, dimeric IgA, and polymeric IgA, all of which interact to some extent with the human IgA Fc receptor (Fc␣RI/CD89).…”