Differential graft resistance of C3H mice pretreated with antitumor drugs against BALB/c bone marrow or lymphoma cells.

Sequential treatment of mice with 5-(3,3'-dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC) and Cyclophosphamide (Cy) produced long-term inhibition of endogenous cells proliferation in the spleen and impairment of classical allograft response, similar to that obtainable with lethal total body irradiation. The growth of BALB/c bone marrow or of virus-induced LSTRA leukemia of BALB/c origin, was studied comparatively in drug-treated or irradiated histocompatible (BALB/c x DBA/2)F1 or allogeneic C3H/HeN hosts. No splenic resistance of Hh type against bone-marrow cells was detected in C3H recipients, either irradiated or drug-treated, confirming previous studies on the Hh susceptibility of C3H strain. In contrast, strong transplantation resistance was detected in the spleen, liver and lung of the same hosts, irradiated or drug-treated, and challenged with LSTRA cells. It follows that Hh-susceptible mice are competent for mounting a localized radioresistant and drug-resistant response, directed against a virus-induced lymphoma.