The role of donor passenger leukocytes in rat skin allograft rejection.

Abstract

There has been much speculation on the role of donor “passenger” leukocytes carried with allografts in the ultimate rejection of these allografts. Results of skin graft donor pretreatment with irradiation, cyclophosphamide, and antilymphocyte serum in various doses and time intervals are presented. Donor pretreatment with irradiation is shown to be superior in prolonging mean graft survival time, and lower doses followed by a longer time interval are shown to be superior to higher doses and a shorter time interval. Much of the difficulty in evaluating previous work on the role of donor passenger leukocytes is attributable to the fact that the exact extent of the donors' hematopoietic chimerism has not been determined. Results are presented using skin graft from donors that within the limits of bone marrow karyotype analysis and fluorscent antibody study of lymph node suspensions are 100% hematopoietie chimeras. Grafts from these donors will not sensitize recipients if removed after 48 hr, but will if left in place for 7 days. Untreated control grafts and irradiated isogeneic repopulated grafts sensitize recipients if left in place 48 hr. From these data, the role of donor passenger leukocytes in rat skin allograft rejection would appear to be limited in extent, probably to the period before vascular and lymphatic connections are established between the graft and its host.