Clinical significance of serologic markers related to red blood cell autoantibodies production after red blood cell transfusion-severe autoimmune hemolytic anemia occurring after transfusion and alloimmunization: successful treatment with rituximab.

BACKGROUND: The association of autoantibody formation with blood transfusion was previously noted. Severe autoimmune hemolytic anemia (AIHA) diagnosed after red blood cell (RBC) transfusion determined us to undertake this study and investigate the incidence and clinical significance of autoantibodies occurring after transfusion by a retrospective review of blood bank and medical records. STUDY DESIGN AND METHODS: We report a lymphoma patient who developed severe autohemolysis after blood transfusion and alloantibody production. The hemolysis was refractory to steroids and chemotherapy and ceased after rituximab. We also retrospectively assessed the blood bank records for a 2-year period to identify the patients who developed autoantibodies after blood transfusion and examined laboratory, clinical features, and outcome.
RESULTS: From January 2005 through December 2006, 375 direct antiglobulin tests (DATs) and 3409 indirect antiglobulin tests (IATs) were found to be positive. Thirty-eight patients with positive DATs and IATs had demonstrable RBC warm-type autoantibodies occurring after blood transfusion; 27 of them had also one or more alloantibodies. Clinical and laboratory signs of hemolysis were absent in all patients (except the case reported). In another 5 patients alloantibodies were retrieved from RBC eluate and serum without evidence of autoantibodies; therefore, a delayed serologic transfusion reaction was diagnosed.
CONCLUSION: RBC autoantibodies are quite commonly found after blood transfusion. Nevertheless, clinically significant AIHA is a rare but at times a life-threatening phenomenon. We describe a first case of successful treatment with rituximab of refractory posttransfusion AIHA. Rituximab must be further evaluated for this indication.