Intravascular hemolysis by IgA red cell autoantibodies

A 66-year-old male patient with severe intravascular hemolysis is presented. Laboratory investigation revealed initially a negative direct antiglobulin test (DAT), suggesting a Coombs-negative hemolytic anemia. Additional testing with monospecific anti-IgA was strongly positive. IgA autoantibodies with anti-e specificity and nonspecific IgA autoantibodies were identified. A diagnosis of IgA-only-associated warm AIHA was made. Treatment included transfusion of multiple e-negative typed red cell concentrates and administration of high-dose prednisone. The pathophysiologic mechanism of the rare IgA-induced warm AIHA is discussed.