Cyclosporin-A abrogates transfusion-induced sensitization and prevents marrow graft rejection in DLA-identical canine littermates.

Previous studies had shown that marrow graft rejection generally did not occur in untransfused dogs given 900-rad total body irradiation and hemopoietic grafts from DLA identical littermates (only 1 of 59 rejected), but was seen in all instances after three preceding transfusions of whole blood from the marrow donor on days -24, -17, and -10 before transplantation (19 of 19 rejected). The present study was undertaken to investigate whether immunization by 3 preceding transfusions of whole blood from the DLA-identical littermate marrow donor could be abrogated by administration of the immunosuppressive agent cyclo-sporin-A, 20 mg/kg/day intramuscularly on days -5 to 0. Seven of 10 dogs showed sustained marrow engraftment. 2 failed to engraft, and 1 dog died to early to be evaluated. It was concluded that immunization to non-DLA antigens by preceding whole blood transfusions could be abrogated in most cases by a short-course of cyclosporin-A before total body irradiation and marrow transplantation, resulting in successful and sustained marrow engraftment.