Effect of time on sensitization to hemophoietic grafts by preceding blood transfusion.

Previous studies have shown that a single transfusion with whole blood from the intended marrow donor 10 days before 1,200 R of total body irradiation (TBI) and marrow grafting can immunize a dog and lead to rejection of the subsequent marrow graft. The present study explored the effect of time on immunization to marrow grafts by preceding blood transfusion. All receipents were given 1,200 R of TBI followed with 4 hr by a hemopoietic graft from an unrelated donor mismatched at the major canine histocompatibility complex. Two groups of recipients were studed. In group 1, 7 dogs were given a transfusion of blood from the marrow donor 24 hr before TBI, and 6 rejected the graft; in group 2, 16 dogs were given transfusion of blood from the marrow donor 3 months before TBI, and 8 rejected the graft. The frequency of rejection in both groups was significantly greater than in untransfused dogs mismatched with their donors at the canine major histocompatibility complex (11 rejections in 67 transplants). The results indicate that exposure to donor blood from 24 hr to 3 months before marrow grafting significantly increases the likelihood of graft rejection.