Induction of Suppressor Activity on B-Cell Differentiation in Human T-Cell Subset without Fc(IgG) Receptors by Levamisole Administration

A single oral dose of 150 mg levamisole was administered to five healthy adults. Circulating Fc(IgG) receptor-bearing T cells (T gamma cells) increased for 5 days after levamisole intake, but total E rosette-forming cells showed no significant alterations. The generation of immunoglobulin-producing cells in the peripheral blood lymphocytes (PBL), which was induced in the in vitro pokeweed mitogen (PWM)-stimulated cultures, was significantly suppressed for 5 days after levamisole administration. Suppressor T-cell activity on B-cell differentiation, which was induced by levamisole intake, was evaluated by co-culturing with allogeneic untreated adult PBL in the PWM system in six other volunteers. A seemingly dose-dependent suppression on B-cell differentiation was exerted by T cells isolated on day 3 of levamisole treatment, but not by T cells differentiation was exerted by T cells isolated on day 3 of levamisole treatment, but not by T cells which were isolated before or on day 14 of the experiment. When T cells were fractionated into two subsets with regard to the presence or absence of Fc(IgG) receptors, suppressor T-cell activity appeared to be generated by levamisole largely in T cells lacking Fc(IgG) receptors, but not in T gamma cells.