In vivo effect of levamisole on cellular and humoral immunity in normal chickens.

The effect of levamisole in vivo was studied on the PHA and Con A responses of chicken peripheral blood lymphocytes and on the in vivo antibody response to a thymus dependent antigen (BSA) and to a thymus independent antigen (Brucella abortus). Levamisole (0.25 mg/kg) increased significantly both the PHA and Con A responses of chicken blood lymphocytes. The antigens were given at the time of enhanced mitogenic responses and a significant increase was observed in both IgM and IgG antibodies to BSA. In contrast, no effect was obtained on antibody responses to Brucella abortus organisms. The results show that levamisole is able to enhance both humoral and cellular immune responses in normal chickens. The effect is probably mediated by the activation of the T cell function and effects only antibody responses to thymus dependent antigen. These findings confirm and extend the observations regarding the ability of levamisole to modulate immune responses.