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 co-cultured 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 co-cultured with CD4+CD25- T cells. The proliferation of cells was assessed by [3H] thymidine incorporation method.
Results: 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.