Transient pure red cell aplasia caused by antilymphoblast globulin after cadaveric renal transplantation

Transient pure red cell aplasia (PRCA) in three consecutive patients receiving ATG for management of kidney graft rejection prompted a systematic study of the effects on erythropoiesis of the ATG preparation used at our institution. We found that 90% of patients treated with rabbit anti-T lymphoblast globulin developed reticulocytopenia (less than 17,000 reticulocytes/mm3), with complete disappearance of reticulocytes in 65% of patients and increased requirement for red cell transfusion. PRCA, with selective aplasia of erythroblasts was confirmed by bone marrow aspiration in 4 patients volunteering for aspiration, and by the kinetic of the disappearance of blood reticulocytes in relation to the beginning of ATG treatment. The nadir of thrombocytes and lymphocytes, blood cells directly destroyed by ATG in circulation, followed the start of ATG treatment within 1 to 4 days. In contrast the nadir of reticulocyte counts occurred later, between day 7 and 13 after ATG was begun, reflecting the fact that toxicity was directed against red cell precursors rather than mature circulating cells. In agreement with these clinical findings ALG was found to be cytotoxic in vitro for erythroid precursors. Analogously to autoimmune PRCA caused by autoantibodies to erythroblasts, this type of PRCA could be viewed as "heteroimmune disease."