IMMUNOMODULATION DUE TO COEXPOSURE TO STYRENE AND DIOCTYL PHTHALATE IN MICE

Pathomorphological and immunological alterations caused by a mixture o f styrene and dioctyl phthalate were studied in albino mice following oral administration of 0.02, 0.03, 0.05 x LD50 of the mixture. The che micals were mixed together proportionate to their respective LD50 valu es and fed in ground nut oil, 5 d/wk for 4 weeks. Histological examina tion of spleen revealed considerable depletion of cellular population of lymphoid follicles which corresponded to the dose dependent decreas e in splenic mononuclear cell population count. The thymic lobules rev ealed slight atrophy but accompanied by a significant increase in thym ocyte population. Correspondingly few significant histological changes were observed in mesenteric and peripheral lymph nodes. The treatment caused impairment of primary humoral immune response to SRBC (IgM) bu t there was a significant increase in response of splenocytes to B-cel l mitogen LPS. There was a suppression of cutaneous delayed type hyper sensitivity and increase in splenic lymphocyte response to T-cell mito gen PHA. Simultaneously, indirect immunity represented by decreased ph agocytosis and enhanced metabolic function of reducing NBT by peritone al exudate cells was observed. The in vitro exposure of vero cells to the mixture caused dose dependent protective effect. The results of pr esent study indicate that subchronic exposure to low doses of mixture of styrene and dioctyl phthalate under certain conditions may modulate some of the immune functions as compared to exposure to either chemic als alone.