Tumor‐specific T helper activity can be abrogated by two distinct suppressor cell mechanisms

Abstract

Tumor‐specific helper T cell activity was detected in the spleens of tumor‐bearing mice using a sensitive, simple and reproducible in vitro assay based on those previously described for soluble hapten‐carrier antigens. Helper activity disappears when the tumor is large. This is coincident with the appearance of two distinct types of suppressor cells: (a) T cells which suppress tumor‐specific T helper responses and (b) non‐T cells which are nonspecific in their action.