Suppressor T cells and the regression phase of syngeneic intradermally developing p-815 mastocytomas.
Thymus cells obtained 6, 8 or 10 days after the intradermal injection of P-815 tumor cells into syngeneic DBA/2 mice were, upon adoptive transfer into new hosts, incapable of abrogating the normally observed tumor regression phase. Transfer of cells from day 8 revealed a tendency toward suppression of regression phases; cells from day 6 or 10 were inert or had a rather immunopotentiating effect. Pretreatment of tumor hosts with cyclophosphamide did not result in more pronounced regression phases, nor did this treatment raise the percentage of surviving animals. Injection of cyclophosphamide after tumor cell inoculation resulted in a slight delay of tumor growth, but not in more pronounced regression nor in higher survival rates. Taken together the data suggest that in a weakly immunogenic and highly malignant tumor, suppressor T cells may play a minor role in the subversion of the host's immune response.
D000818:Animals; D003520:Cyclophosphamide / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D005260:Female; D007116:Immunization, Passive; D012515:Mast-Cell Sarcoma / Q000188:drug therapy / Q000276:immunology*; D051379:Mice; D008811:Mice, Inbred DBA; D009374:Neoplasms, Experimental / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
D003520:Cyclophosphamide