Influence of the properties of skin allografts on the "graft survival promoting effect" of antilymphocyte serum.

Changes in the properties of non-H-2 imcompatible skin allografts, resulting from treating the graft donors with whole-body irradiation, antilymphocyte serum, cyclophosphamide, hydrocortisone, amethopterin and azathioprine, affected differently their survival in the recipients pretreated with normal and antilymphocyte serum. While in NS--pretreated recipients the modified grafts showed the tendency for a prolonged survival, in ALS-pretreated recipients they survived for a shorter time than normal allografts. In ALS-pretreated recipients, also allografts from radiation chimaeras, whose blood-forming system was of the recipient's genotype, survived worse than normal allografts and grafts from the donor syngeneic radiation chimaeras. The findings indicate that a normal physiological state of the graft is necessary for the induction and working of the protective components of the allotrasplantation reaction involved in the graft survival promoting effect of ALS. The significance of passenger leucocytes and of the functional properties of the graft, especially of the reparation cellular and extracellular processes is discussed.