Effects of levamisole on in vitro suppressosr cell function in normal humans and patients with systemic lupus erythematosus.

Levamisole-treated mononuclear cells from normal volunteers or from patients with systemic lupus erythematosus (SLE), when cultured with normal allogeneic lymphocytes, did not significantly influence the ability of the latter cells to proliferate when stimulated with either phytohemagglutinin (PHA) or concanavalin A (Con A). Levamisole, furthermore, did not influence the ability of Con A to induce suppressor cell function from normal mononuclear cells. When mononuclear cells from patients with SLE were treated with therapeutic concentrations of levamisole in the presence of Con A, the drug was unable to restore the ability of the Con A to induce normal suppressor cell function. SLE cells treated with a high concentration of levamisole (60 micrograms/ml) in the presence of Con A did show some suppressor cell activity on normal autologous mononuclear cells activated by Con A, but not by PHA. Although the significance of this latter finding is unclear it appears that levamisole at therapeutic concentrations does not influence in vitro suppressor cell function of normal or SLE mononuclear cells.