Effect of endocrine disrupters on immune responses in vivo

In previous papers we reported that endocrine disrupters (EDs) such as 4,4'-isopropylidene diphenol (Bisphenol A: BPA), bis(2-ethylhexyl) phthalate (EHP) and p-nonylphenol (NP) stimulated proliferative responses and cytokine productions of murine spleen cells and thymus cells in vitro. In this paper we report our studies on the effect of EDs on immune responses in vivo. EDs (10(-5) M) such as BPA, EHP and NP were administered to mice by free drinking for 6 weeks and their immune responses were studied both in vitro and in vivo. EDs did not affect the body weight of the mice, spleen and thymus cell numbers, and serum immunogloburin concentration. The proliferative responses of spleen cells cultured in vitro were not changed by EDs-administration. However, the proliferative responses of thymus cells from EDs-treated mice were enhanced. Furthermore, the immunization of EDs-treated mice with protein antigens resulted in the enhanced production of antibody. These results suggest that EDs have immunomodulating activities in vivo.