[Immunobiological fundamentals of primary graft rejection (author's transl)].

Graft rejection caused by genetic differences between donor and recipient is an immunological reaction of transplantation antigens with mechanisms of primarily cellular immunity, and later on even of humoral immunity. For initiating the immune response of the recipient three stages have to be distinguished: 1. Recognition of determinant groups of transplantation antigens by menbrame receptors at the surface of immunologically competent lymphocytes. 2. Differentiation and proliferation of immunologically activated lymphoid cells into cellular antibodies and plasma cells, the receptor molecules of which could be identified as immunoglobulins and which are sent into the blood as circulating humoral antibodies, , partially as complement fixing ones. 3. Effector phase, in the course of which the lysis of the graft is caused by target cell destruction. Many problems still remain unsolved, but now as ever, the basis of most experimental studies is still formed by Burnet's clonal selection theory.