Acute hemolytic transfusion reaction associated with anti-Mta: case report and review of the literature

BACKGROUND Mt(a) (MNS14) is a low-prevalence antigen of the MNS system. A few cases of hemolytic disease of the fetus and newborn caused by anti-Mt(a) have been reported in the literature, but up to now this antibody has never been associated with a hemolytic transfusion reaction (HTR). CASE REPORT A 38-year-old male with sickle cell disease undergoing exchange transfusion presented with shivering, nausea, dyspnea, and pain in the lower limbs. Biologic parameters showed increased hemolysis. The administered red blood cell (RBC) units had been issued by electronic crossmatch due to a negative antibody screening test. In the posttransfusion investigations, crossmatch of the transfused RBC units with the patient's serum showed incompatibility of one unit. The presence of an antibody against a low-prevalence antigen was suspected and further serologic testing was performed for identification. RESULTS Anti-Mt(a) was identified in the patient's serum. The RBCs of the incompatible unit implicated in the HTR were Mt(a+). An eluate of a posttransfusion blood sample of the patient was nonreactive with the incompatible RBCs, and the direct antiglobulin test was negative. CONCLUSION To our knowledge, this is the first case report of an HTR associated with anti-Mt(a).