Suppressor T cells with histamine type II receptors in chickens bearing chemically induced fibrosarcomas.

Immunity to a local (wing web) challenge with transplantable, chemically induced tumors, such as CHCT-NYU-4, can be transferred to histocompatible SC chickens with intravenously injected splenic T cells from tumor-immune chickens. Simultaneous iv injection of splenic T cells from chickens bearing progressively growing CHCT-NYU-4 prevents the expression of this adoptive systemic tumor immunity. The splenic suppressor T cells are B-L(Ia) positive and adhere to dishes coated with cimetidine-protein conjugate, suggesting that they bear type II histamine receptors (H2R). Intravenous injection of gamma-irradiated CHCT-NYU-4 cells 7 days prior to a local challenge with the same tumor promotes growth of a normally suboptimal tumor cell dose such that the incidence of progressive tumor growth is significantly increased. Concomitant treatment with the H2R antagonist, ranitidine, inhibits tumor growth of an optimal tumor dose challenge and promotes induction of tumor immunity. However, this drug cannot reverse the effect of iv injected tumor cells. Another drug with reported antisuppressor cell activity, cyclophosphamide (50 mg/kg), injected 1 day prior to challenge causes a transient inhibition of tumor growth. Injection of this drug on Day 7 does not have a significant effect by itself but, in combination with the Day-1 pretreatment, a significant inhibition of tumor growth by size and tumor incidence measurements is obtained. These results indicate that manipulation of immunity to transplantable fibrosarcomas in the chicken is possible with drugs acting on suppressor cells.