[Regulation of immunological balance between TH1/TH2 and Tc1/Tc2 lymphocytes by prostaglandin E2]

This study was purposed to investigate the effect of prostaglandin E2 (PGE2) on proliferation of peripheral blood T lymphocytes, and to evaluate the regulatory role of PGE2 on immunological balance between Th1/Th2 and Tc1/Tc2 lymphocytes. The peripheral blood mononuclear cells (PBMNC) were stimulated by anti-human CD3 monoclonal antibody (mAb) and anti-human CD28 mAb, and were cultured in the presence of different concentration of PGE2 for 120 hours. The proliferation of peripheral blood T lymphocytes was assayed according to the manufacture protocol of BrdU Kit; the IFN-gamma and IL-4 levels in supernatants cultured for 24, 48, 72 and 120 hours were detected by ELISA; the ratios of CD4+IL-4+ T cells/CD4+ IFN-gamma+ T cells and CD8+IL-4+ T cell/CD8+IFN-gamma+ T cells were determined by flow cytometry. The cells cultured without PGE2 were used as control. The results indicated that (1) with the raising of concentration of PGE2, the inhibitory rate of T cell proliferation in vitro significantly increased (p=0.001). There was significant positive correlation between inhibitory rate of T cells and PGE2 concentration (correlation coefficient=0.889, p=0.000). (2) the difference between the IFN-gamma concentrations in supernatant cultured for 120 and 72 hours in test groups had no statistical significance (p=0.917). The IFN-gamma concentration increased continually with prolonging of culture time in control group (p=0.046). The IFN-gamma concentrations produced at different times in test group were significantly lower compared with those in control group (p<0.05). The IL-4 concentrations produced at different time had no significant change in test groups (p=0.400). The IL-4 concentration in 24 hours in control group was significantly higher than that at 48, 72 and 120 hours in control group (p=0.007, 0.003 and 0.002). After cultured for 24 hours the IL-4 concentration in test group was significantly lower than that in control group (p=0.037), but after cultured for 48, 72 and 120 hours, the IL-4 concentration in test group did not show statistical difference in comparison with control group (p>0.05). (3) the proportions of CD4+IFN-gamma+T cells in test group and in control group had no significant difference (p=0.767). The proportion of CD4+IL-4+T cells in test group was slightly higher than that in control group (p=0.051). The ratio of CD4+IL-4+T cells to CD4+IFN-gamma+ T cells in test group was significantly higher than that in control group (p=0.011). The proportions of CD8+IFN-gamma+ T cells in test group and in control group had no statistical difference (p=0.441). The proportion of CD8+IL-4+T cells in test group was significantly higher than that in control group (p=0.015). The ratio of CD8+IL-4+ T cells to CD8+IFN-gamma+ T cells in test group were obviously higher than that in control group(p=0.038). It is concluded that the PGE2 inhibits the proliferation of T lymphocytes in vitro. PGE2 influences the production of IFN-gamma and IL-4, and significantly influences peak appearance of IFN-gamma produced by T lymphocyte. PGE2 can continuously inhibit the production of IFN-gamma, but its continuous effect on IL-4 is no significant. PGE2 enhances the ratio of CD4+IL-4+T lymphocytes to CD4+IFN-gamma+T lymphocytes and the ratio of CD8+IL-4+T lymphocytes to CD8+IFN-gamma+T lymphocytes, and regulates development of T cells toward Th2/Tc2 cells.