Effect of sub-chronic endosulfan exposure on humoral and cell-mediated immune responses in albino rats

The present study was designed to evaluate the effect of sub-chronic doses of endosulfan on humoral and cell-mediated immune (CMI) responses in albino rats. Male albino rats were given a diet containing 5, 10 or 20 ppm endosulfan for 8-22 weeks and immunized with tetanus toxoid in Freund's complete adjuvant subcutaneously 20 days before terminating the exposure. The humoral immune response was studied by serum globulin level, immunoglobulin (IgM and IgG) concentration and antibody titre against tetanus toxoid. The CMI response was studied by leucocyte migration inhibition (LMI) and macrophage migration inhibition (MMI) factors. The antigen-induced increases in serum globulin fraction and immunoglobulin level were reduced at high doses of the endosulfan after 12 weeks of exposure. Antibody titre was significantly decreased in endosulfan-exposed rats at 10 and 20 ppm levels and a consistent trend was observed. Rats in the 10 and 20 ppm dose groups had significantly depressed LMI and MMI responses. Results obtained in this study revealed marked suppression of the humoral and CMI responses in rats administered with sub-chronic doses of endosulfan. Both cellular and humoral immune responses were decreased in a dose-time dependent pattern. Suppression of immune responses by endosulfan is clearly an important aspect of its toxicology.