The detrimental effects of environmental pollutants on the health of the individual are generally accepted, although the mechanisms of these effects remain to be incompletely understood. In the present study, we examined the effects of B[a]P, 2-BP, phenol and TCDD on proinflammatory cytokine gene expression in mice spleen cells which were stimulated with anti-CD3. 10-9M TCDD increased IFN gammar and TNF alpha gene expression, but suppressed IL-1 gene expression. 10-6M phenol inhibited IL-1, IL-6 and TNF alpha gene expression, and 10-6M of 2-BP downregulated TNF alpha gene expression. However, 10-6M of B[a]P did not influence on IL-1, IL-6, IFN gammar and TNF alpha gene expression. These findings suggest that TCDD may impair the immune functions of mice by enhancing proinflammatory cytokines production, whereas phenol and 2-BP may impair the functions by inhibiting the production of these cytokines.