Inhibition of antilymphoma allograft response in normal and lethally irradiated mice by cyclophosphamide (NSC-26271) and isophosphamide (NSC-109724).

Cyclophosphamide and isophosphamide (an analog) were tested for their effect on the antilymphoma allograft reaction in normal and lethally irradiated mice. Both drugs were effective in abrogating the classic allograft response if given 1 or 3 days before the tumor challenge. While the drugs also inhibited the hemopoietic-histocompatibily response, they were effective when adminstered 7 days before challenge. It is suggested that the activity of various immunosuppressive agents could be compared for their effect on the hemopoietic-histocompatibility system to select the best agent for transplantation of bone marrow or bone marrow or bone marrow-derived cells. Drug toxicity, as well as the effect of the drugs on humoral response and DNA synthesis, was also compared. While isophosphamide was found to be less toxic than cyclophosphamide, the effect of humoral response and DNA synthesis was comparable.