Adoptive immunity to the guinea pig line 10 hepatoma and the nature of in vitro lymphoid-tumor cell interactions.

Adoptive transfer of spleen cells from specifically immunized donors to nonimmunized recipients was used to study tumor immunity in vivo to the syngeneic line 10 guinea pig hepatoma. Hepatoma cells cultured as monolayers on fibronectin-coated surfaces served as targets for immune splenocytes in a 3H release cytotoxicity assay in vitro. An antigenically distinct syngeneic guinea pig hepatoma (line 1) was used to study the specificity of adoptive systemic immunity and of the cytotoxicity in vitro. The protection afforded by adoptive immunization against challenge with hepatoma cells was tumor line specific, while in most cases cytotoxicity in vitro was not. The in vitro cytotoxic effect was abolished after absorption of the immune spleen cells with monolayers of either line 10 or line 1. In contrast, the in vivo tumor-specific rejection activity of line 10 immune spleen cells was depleted after absorption with line 10 but not with line 1 or other control monolayers. These studies revealed that the immune cells mediating cytotoxicity in vitro were functionally distinct from those conveying adoptive protection in vivo. Immune cells possessed receptors for tumor-specific rejection antigens on hepatoma cells, and their interaction did not lead to destruction of the neoplastic cells in vitro.