Hydrocortisone reverses the suppression of immunoglobulin synthesis by concanavalin A-activated spleen cell supernatants.

Supernatants of concanavalin A (Con A)-activated human spleen cells have been previously shown to inhibit polyclonal immunoglobulin (Ig) biosynthesis by pokeweed mitogen (PWM)-stimulated human spleen and peripheral blood mononuclear cells. In the present study, hydrocortisone was added at the beginning of in vitro culture to determine whether it might influence the immunoregulation of polyclonal IgG, IgA and IgM biosynthesis by PWM-stimulated human spleen and peripheral blood mononuclear cells. Hydrocortisone (10(-5) m) mildly increased (15 +/- 9%; mean +/- s.e.m.) polyclonal Ig biosynthesis when added to PWM-stimulated human mononuclear cells. The addition of supernatants from Con A-activated human spleen cells to PWM-stimulated human spleen and peripheral blood mononuclear cells significantly (P less than 0 . 001) suppressed (94 +/- 2%) polyclonal Ig biosynthesis. In contrast, when hydrocortisone (10(-5) m) was added together with Con A supernatants to PWM-stimulated cells, there was no significant suppression (6 +/- 13%) of polyclonal Ig synthesis. Thus, one mechanism by which hydrocortisone can influence Ig biosynthesis is by blocking the suppressive effect of a soluble suppressor factor secreted by Con A-activated human spleen cells.