4+CD25+Foxp3+调节性T细胞在脑型疟疾发生中的作用研究

ITo investigate activation characteristic and correlation with disease progression of regulatory T cells (Tregs) during Plasmodium. berghei ANKA infection. C57BL/6 and BALB/c mice were infected by intraperitoneal injection of 1×106 P.berghei ANKA parasitized erythrocytes. Parasitemia of individual mice was monitored by the microscopic examination of blood smear stained with Giemsa. Spleen cell suspension was prepared from the mice sacrificed on days 0、3、5、8 post infection (p.i.). Applying flow cytometry to quatitatively analyze the numbers of Tregs in total spleen CD4+T cells dynamically. The levels of IFN-γ and IL-10 in spleen supernatants were measured by ELISA kits. C57BL/6 mice died with cerebral malaria (CM) between days 8 and 11 p.i., while BALB/c mice survived until weeks 3-4 after infection and died of anemia and overwhelming parasitemia. The absolute number of Tregs in the spleen started to elevate after infection with the peaks on day 3 p.i. in CM-susceptible C57BL/6 mice or CM-resistant BALB/c mice，and gradually reduced in the later infection from day 5 p.i. to day 8 p.i., C57BL/6 mice showed the most significant decline in the numbers of Tregs on day 8 p.i.. The numbers of Tregs in BALB/c mice were significantly higher than that in C57BL/6 mice during infection. IFN-γ and IL-10 in cultured splenocyte supernatants of two mouse strains began to increase after infection with peaks on day 5 p.i. and decline on day 8 p.i compared to the peak on day 5 p.i. The results indicated slight decline of IFN-γ and significant decline of IL-10 in C57BL/6 mice; significant decline of IFN-γ and slight decline of IL-10 in BALB/c mice on day 8 p.i.. IFN-γ in C57BL/6 mice were significantly higher than that in BALB/c mice. And the level of IL-10 in the former was lower than that in the latter. These results suggest that Tregs mediate the development of cerebral malaria by modification of inflammatory response.