Combined sickle cell disease and autoimmune hemolytic anemia.

Four patients experienced combined sickle cell disease and autoimmune hemolytic anemia within the past ten years. A fifth patient had positive direct antiglobulin test results without verified autoimmune hemolysis. Severely accelerated hemolysis was observed in four patients; anemia was severe, and the reticulocyte count rose into the 60% to 88% range. During the period of active autoimmune hemolysis, decline of the reticulocyte count rose into the 60% to 88% range. During the period of active autoimmune hemolysis, decline of the reticulocyte count into the 6% to 16% range was associated with rapid decrease in the hemoglobin level, requiring transfusion. All five patients were already alloimmunized by transfusions administered before onset of the autoimmune hemolytic anemia; two or more allospecificities were identified in four of five patients. The presence of autoantibody notably compromised compatibility testing; three patients experienced posttransfusion hemoglobinuria, and in vivo cross matching with 51Cr-labeled donor RBCs was employed on three occasions. All patients responded to corticosteroids; mercaptopurine was also administered to one patient. The direct antiglobulin test result reverted to negative in all patients after hospital discharge.