Antigen-specific and nonspecific mediators of T cell/B cell cooperation. I. Evidence for their production by different T cells.

Evidence is presented for two types of helper T cells in the mouse specific for a protein antigen, keyhole limpet hemocyanin (KLH). The first cell is able to help B cells respond to the hapten, trinitrophenyl (TNP), when coupled to KLH presumably through the participation of KLH-specific T cell factors. The second helper cell when stimulated with KLH is able to help B cells respond to red blood cell antigens, but not TNP-KLH, through the production of a non-antigen-specific factor. Both types of helper cells were shown to be present in the spleens of KLH-primed mice, although they occurred with different frequencies. They were shown to be different T cells by their segregation from each other in vitro at limiting dilution.