In Vitro Immune Response of Human Peripheral Lymphocytes

Abstract

Con A‐stimulation of human peripheral T lymphocytes induced both suppressor and helper T cells. Con A‐generated suppressor T cells inhibited PWM‐indueed IgG and IgM production in PBL. Lower concentrations of Con A (0.5 μg/ml) or shorter incubation periods (6 to 24 hr) induced mainly helper T cells, while higher concentrations of Con A (10 μg/ml) or longer incubation periods (at least 48 hr) induced suppressor T cells. Con A‐generated suppressor T cells were sensitive to mitomycin treatment and exerted their suppressor function on the early phase of differentiation and/or proliferation of B cells but not on the final differentiation of B cells to Ig‐producing cells. The identity of the MHC was not required for the expression of suppressor function. Suppressor T cells competed with helper T cells in PWM‐induced Ig‐production of PBL. This experimental system can be applied to estimate the regulatory function of T cells in several disease states.