Effect of preliminary injection of allogeneic cells on transplantation immunity in mice receiving cyclophosphamide

Injection of 1×10⁸ C57BL/6 mouse spleen cells into CBA mice 1 day before treatment with cyclophosphamide (CP) was shown to promote survival of 2×10⁷ allogeneic or semiallogeneic cells injected later (3–6 h after CP). The criterion of survival was the ability of the donor cells to produce antibodies against sheep's red blood cells in recipients tolerant to this antigen. Injection of 1×10⁸ allogeneic cells 2 days before CP treatment had no protective effect. After intravenous immunization with allogeneic cells, killer cells began to appear in the recipient's spleen as early as on the 2nd day, and their number reached a maximum on the 5th day. The results suggest that CP eliminates the recipient's lymphocytes responding to transplantation antigens, but the killer cells already formed are resistant to the action of CP.Laboratory of Immunologic Tolerance, N. F. Gamaleya Institute of Epidemiology and Microbiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR P. A. Vershilova.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 2, pp. 192–194, February, 1978.