[Severe hemolytic anemia caused by anti-AB in renal transplantation with minor ABO incompatibility]

A 54 year-old woman subjected to renal transplant with minor ABO incompatibility developed clinically severe anti-AB haemolytic anaemia. On the 13th day after transplantation the patient had: haemoglobin, 7.5 g/dL, unconjugated bilirubin, 393 mumol/L (23 mg/dL), and undetectable haptoglobin levels. Positive direct antihuman globulin test was found, and an IgG antibody capable of binding complement and with anti-AB specificity was found upon studying the eluate. Immunosuppressive therapy improved the clinical picture, although antibodies could still be detected one month later. Clinically significant immune haemolysis after renal transplantation appears in about 10-15% of those cases having antibodies against the host's antigens. The peak red-cell destruction is seen one to two weeks after grafting, and haemolytic signs may last for about three weeks. Although self-limited, this condition may achieve high severity. The duration and severity of haemolysis depend upon the density of antigen sites on the surface of the host's red-cells, his secretor trait, the presence or absence of complement activation and the immunosuppressive therapy including cyclosporin. Several cases of anti-A and anti-B specificity have been reported, but anti-AB specificity had not been previously found; this fact is probably related to the scarce interest paid to its search thus far.