Estradiol (E2) At Pregnant Level Differentially Regulates The Activation Of Spleen Cells Derived From Normal And Immunized Mice

Objective To investigate pregnant level of estradiol (E2)-mediated differential regulation of ConA-induced activation of spleen cells from normal and antigen-primed mice.Methods Balb/c mice were immunized with BSA and complete Freund's adjuvant. The level of BSA-specific IgG in serum was detected by indirect ELISA. The proliferation of ConA-activated spleen cells was measured by MTT test. The gene transcription of co-stimulators and cytokines was assayed by RT-PCR. The levels of IFN- γ and IL-4 protein in the supernatants of spleen cell culture were detected by sandwich ELISA.Results No difference was found in BSA-specific IgG levels between the mice treated and untreated with E2. E2 was found to be able to stimulate the proliferation of naive spleen cells but inhibit the proliferation of BSA-primed spleen cells. In naive spleen cells, the transcription of CTLA-4 and B7-1 gene was found to be down-regulated, while the transcription of B7-2 gene was up-regulated by E2. In BSA-primed spleen cells, however, only the transcription of CTLA-4 gene was up-regulated by E2.E2 was found to up-regulate the transcription of IFN-γ, IL-2 and IL-12p40 gene and down-regulate the transcription of IL-4 and TGF-β gene in naive splenocytes. As for antigen-primed spleen cells, E2 treatment in vitro up-regulated the transcription of IL-4 and IL-10 gene, no regulatory effect was found on the transcription of IFN-γ, IL-2, IL-12p40 and TGF- β gene;E2 treatment in vivo augmented the expression of IFN-y, IL-2, IL-12p40 gene, and the expression of IL-4 and IL-10 gene was alsoincreased by E2 treatment in vivo. The level of IFN-y was increased in the supernatants from both naive and primed spleen cells cultured in the presence of E2. The level of IL-4 was increased in the supernatant from the primed spleen cells cultured in the presence of E2 but decreased in the supernatant from the naive spleen cells cultured in the presence of E2.Conclusion Pregnant level of E2 differentially regulates activation and differentiation of naive and primed spleen cells in aspects of cell proliferation, expression of co-stimulator genes such as CTLA-4, B7-1 and B7-2;expression of cytokine genes including IL-2, IL-4, IL-10, IL-12, IFN-y and TGF-P;and the production of IL-4 and IFN-y. The differential regulation exerted by E2 depends upon the differentiation stage where the activated lymphocytes exist.