Specific T helper and suppressor cells and factors induced in vitro to the hapten NP

Nitrophenyl (NP)-specific helper cells and suppressor cells were induced in vitro using NP-T4 bacteriophage as antigen. These cells could mediate their effects also by secreted effector molecules, helper and suppressor factors. The function of both NP-specific helper and suppressor cells was abolished by treatment with anti-Thy1.2 plus C', but they were not retained on nylon wool columns, suggesting that NP-specific helpers and suppressors were T cells. The membrane phenotype of both NP-specific helper and suppressor cells was found to be Ly1+2+I-J+(I-A-). The secreted effector molecules, helper and suppressor factors which mediate helper or suppressor function, bound to NP immunoadsorbents and are NP-specific in their function. They do not have conventional Ig determinants, but both bear determinants coded by the I-J subregion of H-2. The unusual phenotype of NP-specific helper and suppressor cells is discussed, as is the potential use of these hapten-specific T cells and their secreted effector molecules in increasing our understanding of T-cell receptors, effector molecules and the fine specificity of the interacting network in the regulation of immune responses.