Diethylstilbestrol: Suppression On Splenic T Cell Subsets Of BALB/c Pregnant Mice Infected With Toxoplasma Gondii And Effect On Vertical Transmission

Purpose of studyTo invest the change of splenic T cell subsets of BALB/c pregnant mice infected with Toxoplasma gondii, suppression of Diethylstilbestrol on splenic T cell subsets of BALB/c pregnant mice infected with T. gondii, effect of Diethylstilbestrol on vertical transmissionMaterials and methods6-8 weeks old BALB/c pregnant mice were divided into four groups: control group(C), control group infected with T gondii(TC), group treated with low doses of DES(TD1) and group treated with high doses of DES (TD2). At 8 day of gestation, animals of group TC, TD1 and TD2 were infected with 400 tachyzoites of RH strain. Mice in group C were injected intraperitoneally (i.p) 100ul normal saline. On day 10 and 13 of pregnancy, mice of group C, TC, TD1/TD2 were treated with soya-bean oil (200ul), soya-bean oil (200ul), DES (1ug/100g), DES (10ug/100g), respectively.Mice were killed on day 12, 14, 16, 18 of pregnancy, respectively. The E2 level of serum was tested by RIA; The number of splenic CD4+ and CD8+ T cells were detected by FACScan; The thymus was weighed; the rate of live fetus was counted; Whether the embryos in uteri were infected with T. gondii was identified by ELISA.ResultsThe T cell population of all times in TC group increased as time went on. But the trend of CD4+ and CD8+T cells are different, which increased at first and declined later for CD4+ T cells(35.25%, 40.84%, 39.14%, 36.99%) and raised always for CD8+T cells (24.42%, 3 1.01%, 40.22%, 47.50%) . As a result, CD4+: CD8+ ratio declined. Compared with group C, there were an increase in the number of T cells and a decrease in CD4+: CD8+ ratio of spleen of group TC. It demonstrated that both CD4+ and CD8+ T cells were important in the development of protective immunity and CD8+ T cell subset was the major population in controlling T. gondii.Compared to group C, the E2 level of group TC rose in all times, the splenic CD4+and CD8+ T cell population went up, CD4: CD8 ratio declined, the thymus weight increased. All these suggest that estrogen can reduce T cell population and thymus weight of mice infected with T. gondii, especially the number of CD8+ T cells. As a result of this inhibition, CD4: CD8 ratio increased.The rate of live fetus and vertical transmission of T. gondii in TC group are 66.28%和 48.83%. With the treatment of DES, compared with group TC, the rate of live fetus and vertical transmission of group TD1 increased significantly(80.00%, 74.44%), the E2 level of group TD1 rose; all the data above of group TD2 showed no obvious difference except that the serum E2 level was higher on day 12 of gestation. As for the splenic CD4+and CD8+ T cell population, compared with group TC, it declined in TD1 group and had no difference in TD2 group. It suggests that appropriate dose of DES can inhibit the proliferation of splenic T cells. The inhibition of DES to CD8+ T cell subset is more significant so that the rate of T. gondii vertical transmission increased. The E2 level of TD2 didn't change much. It had noobvious effect on both CD4+ and CD8+ T cell population and the rate of T. gondii vertical transmission. It might because the administration of a higher dose DES has inhibited the secretion of endogenous estrogen.ConclusionBoth CD4+ and CD8+ T cells take part in the anti-infection of T. gondii. And CD8+ T cell subset is the major population in controlling T. Gondi. Estrogen can suppress the proliferation of splenic CD4+ and CD8+ T cells and the thymus weight. A certain dose of DES can raise the rate of live fetus and the vertical transmission of T. gondii simultaneously, which shows that controlling infection and keeping pregnancy are paradox and DES is benefit for keeping pregnancy and is harmful for controlling infection.In conclusion, it's one of the major factors for the increasing of the rate of vertical transmission that estrogen suppresses splenic T cells, especially CD8+ T cell subset.