Abstract: 【Abstract】 Objective To study the role of Schistosoma japonicum Mr 22 600 particulated-antigen on dendritic cells （DCs） and CD4+CD25+ regulatory T cells. Methods In in vitro experiments， DCs were pulsed with Sepharose 4B coupling rSj22.6/26GST and soluble rSj22.6/26GST, respectively. The surface molecules of DCs were detected by flow cytometry and the function of DCs was detected by mixed lymphocyte reaction. For the reduction of CD4+CD25+ T cells, DCs pulsed with Sepharose 4B coupling rSj22.6/26GST and soluble rSj22.6/26GST, respectively, were cocultured with CD4+ T cells isolated from the spleen cells. The percentage of CD4+CD25+ Foxp3+ T cells in CD4+ T cells was detected by flow cytometry. In in vivo experiments, BALB/c mice were immunized with Sepharose 4B coupling rSj22.6/26GST, Freund′s adjuvant emulsified rSj22.6/26GST, rSj22.6/26GST, Sepharose 4B, Freund′s adjuvant and PBS, respectively. The percentage of DCs in draining lymph nodes and the percentage of CD4+CD25+Foxp3+ T cells in spleen cells were detected by flow cytometry. To analyze the inhibitory roles of CD4+CD25+ T cells on CD4+CD25- T cells, CD4+CD25+ T cells were separated from mice immunized with Sepharose 4B coupling rSj22.6/26GST and Freund′s adjuvant emulsified rSj22.6/26GST, respectively, and cocultured with CD4+CD25- T cells. The proliferation of cells was assessed by ［3H］ thymidine incorporation methodResults In vitro， the expression rate of the surface molecules of CD40, CD80 and CD86 on the soluble antigen pulsed DCs were （43.5±6.2）%, （37.7±0.1）%, and （71.4±1.4）%, respectively. But on the Sepharose 4B coupling antigen pulsed DCs, they were （31.2±5.4）%, （32.0±1.6）%, and （63.8±1.0）%, respectively, which suggested that the Sepharose 4B coupling rSj22.6/26GST had less stimulating roles on DCs maturation. Furthermore, addition of DCs pulsed with Sepharose 4B coupling rSj22.6/26GST caused the expanding of CD4+CD25+ T cells. In vivo, immunization of Sepharose 4B coupling rSj22.6/26GST increased the number of CD4+CD25+ T cells. CD4+CD25+ T cells separated from Sepharose 4B coupling rSj22.6/26GST immunized mice had stronger inhibitory ability （cpm 1 420±335）, compared with that of mice immunized with soluble antigen （cpm 3 558±147）. Conclusion In contrast to the Freund′s adjuvant emulsified antigen, immunization with Sepharose 4B coupling rSj22.6/26GST increases the number of CD4+CD25+ T cells, which showed stronger inhibition on the CD4+CD25- T cell proliferation, and the mechanism of which may be involved in DCs maturation.

Key words: Schistosoma japonicum, CD4⁺CD25⁺ T cells, Dendritic cells, Particulate antigen