Restoration of T-cell function in aged mice with long-term administration of levamisole

Abstract

The in vivo effect of levamisole on antibody production against sheep red blood cells (SRBC) in aged mice was examined. Aged C57BL/6 mice were treated with levamisole, 2.5 mg/kg per os, for 5 months. The long-term administration of levamisole restored the ability of immune response to SRBC. The effect of levamisole on B cells was examined by an in vitro coculture technique. There was no change in the number of plaque-forming cells (PFC), indicating that levamisole did not act on B cells. Suppressor function of T cells after long-term administration of levamisole was also examined. Concanavalin A (Con A)-treated spleen cells from aged mice previously treated with levamisole suppressed the number of PFC of cocultured spleen cells from young mice, but Con A-treated spleen cells from aged control mice (no levamisole treatment) failed to suppress the number of PFC. The in vitro effect of levamisole was assessed by the number of PFC. The number of PFC was not altered significantly when levamisole was added to the culture medium. These results indicate that long-term administration of levamisole to aged mice can restore helper as well as suppressor T-cell function, and suggest that levamisole itself is not active in vitro but exerts its effect through metabolites in vivo.