Immunoregulation by T cells. I. Characterization of the IE(k)-specific Lbd self-reactive T cell clone that helps, suppresses and contrasuppresses B cell responses

This paper describes an L3T4⁺, Lyt-2^- cloned T cell line of CBA/N origin that is specific for IE(k)-encoded products. Splenic dendritic cells are the predominant stimulatory populations for Lbd cells, being approximately 100 times more effective than large activated B cells. Small B cells and T cells are nonstimulatory. Ldb cells help large B cells to make polyclonal antibody responses, but are unable to activate small B cells and to replace antigen-specific helper T cells in T cell-dependent responses to phosphorylcholine or sheep red blood cells. In the presence of antigen-specific helper T cells, Ldb can amplify, suppress, or contrasuppress T cell funciton, depending on the type and relative ratios of antigen-reactive cells. We explain our findings as a consequence of the self reactivity among helper T cells.