Immunoregulatory circuits among T-cell sets. Identification of a subpopulation of T-helper cells that induces feedback inhibition.

Purified Ly1 cells induce other T-cell sets to exert potent feedback inhibitory activity and this T-T interaction has been shown to play an important role in regulating in vivo immune responses. Approximately 2/3 of Ly1 cells also express the Qa1 surface phenotype (Ly1:Qa1+ cells). The experiments reported here indicate that Ly1:Qal+ cells are responsible for induction of feedback inhibition and that signals from both Ly1:Qal+ cells and Ly1:Qal- cells are required for optimal formation of antibody by B cells.