Abstract
These studies describe the conditions under which antibody-forming cells and TDTH cells are selectively induced in vitro. TDTH cells are preferentially stimulated when high doses of antigen are included in the culture. Antibody-forming cells, on the other hand, are optimally stimulated with a 100 to 1000-fold less concentration of antigen. The conditions that optimally stimulate TDTH cells also induce a population of suppressor T cells that inhibit the antibody response. However, although their inductive requirements are similar, the suppressor T cells of antibody formation are a distinct subpopulation of cells from the TDTH cells. Whereas the suppressor T cells are LY-1-, 2+, 4-, 6+, and Ia+; the TDTH cells are Ly-1+, 2+/-, 4-, 6+, and Ia-. Furthermore, the DTH cells are sensitive to high doses of irradiation, whereas the suppressor cells are resistant. Based on the Ly phenotype and the kinetics of suppression, the suppressor T cells are not the "feedback suppressors" that have been identified in other systems. The system described in this paper provides a means whereby the cells that regulate humoral and CMI can be studied in vitro.
