Cytophilic and cytotoxic antibodies in sera of rabbits after allogeneic skin grafts.

The appearance, distribution in serum fractions, and specificity of cytophilic and cytotoxic antibodies in rabbits after skin allotransplantation were investigated. The sera were obtained from rabbits receiving three subsequent skin allografts across the RL-A barrier. The direct cytophilic test and the microcytotoxic test using the graft recipients sera and lymphocytes from the donor rabbits, as well as lymphocytes from other rabbits were performed. In all the sera under investigation both cytophilic and cytotoxic antibodies were found. The specificity of cytotoxic antibodies was directed against rabbit histocompatibility antigens (RL-A), in contrary to cytophilic antibodies, which were strongly active with the donor lymphocytes, and to a somewhat lesser degree with other lymphocytes, regardless their RL-A constitution. Posttransplantation cytophilic and cytotoxic antibodies were present in the gamma1 and gamma2 classes of immunoglobulins and absent from the IgM immunoglobulins. It is concluded, that allografted rabbits develop, besides the known cytotoxic antibodies, also cytophilic antibodies, not connected with the strong histocompatibility antigen system.