Isolation and characterization of an autoreactive T cell clone which regulates differentiation of activated B cells

We have isolated T cell clones from lymph node cells obtained from antigen primed CBA/N mice. In addition to producing FGG-reactive, MHC restricted T cell clones we unintentionally generated several clones which displayed a marked proliferative capacity when cultured with syngeneic filler cells alone. One of these self-reactive T cell clones, designated L, was selected for further studies of the AMLR at the clonal level. Clone L is Thyl⁺, Lytl^-, Lyt2^-, GK1.5⁺, Ia^- and slg^-. It recognizes class II (IA(k) + IE(k)) MHC encoded determinants in the absence of xenogeneic serum. Clone L cells activated by syngeneic cells of concanavalin in A release IL-2, T cell replacing factor and B cell differentiation factor. These characteristics and the lack of cytotoxic function indicate that clone L belongs to a helper T cell subset. Studies of the stimulating population clearly show that adherent denderitic cells are the most important cellular component among non-activated splenic cells. Among mitogen-activated spleen cells, LPS-induced B cell blasts are potent stimulators. Interestingly, clone L while failing to activate small, resting B cells can continue the differentiation of large, activated B cells into PFC. Therefore, this autoreactive T cell clone represents an important amplification component in B cell response. (NIH-grants-AI-14530 and GM-5-732).