Glucocorticosteroid enhancement of immunoglobulin synthesis by pokeweed mitogen-stimulated human lymphocytes.

We studied the role of the T lymphocyte in GCS enhancement of PWM-stimulated IgG synthesis by human peripheral blood mononuclear cells. Purified T or B lymphocyte subpopulations were pretreated with 10(-6) M prednisolone or recombined at various T:B ratios and 10(-6) M prednisolone was added. PWM-stimulated IgG synthesis was measured in the culture supernatants at 8 days by radioimmunoassay. Addition of prednisolone to cultures of autologous and allogeneic reconstituted mixtures of T and B lymphocytes resulted in enhancement of PWM-stimulated IgG synthesis. This effect was observed with constant and increasing numbers of lymphocytes in culture, independent of T:B ratio and occurred with purified B lymphocytes containing monocytes. Pretreatment of purified B lymphocytes containing monocytes but not purified T lymphocytes with prednisolone enhanced PWM-stimulated IgG synthesis in reconstituted mixtures of T and B lymphocytes. We propose that GCS enhancement of PWM-stimulated IgG synthesis by human mononuclear cells is independent of T lymphocyte regulation.