Development Of Adult Worm And Granulomatous Pathology Are Regulated By B Cells In Mice Infected With Schistosoma Japonium

Schistosomiasis by S. japonium is a serious zoonosis in our country now. Tradition opinion concerning the relationship between hosts and parasites is that parasites damage their hosts and meanwhile the hosts bring up resistance against the invading parasites through activation of immune response. It is good for inhibiting parasite development and damages by oviposition that we study adult worms development in vivo and immune-regulating mechanism. Schistosoma blood flukes are dependent on signals from host CD4+T cells to facilitate parasite growth and development. Thus it is not clear whether B cells mediate parasite development, reproduction and egg granuloma formation of schistosomes without the help of CD4+T lymphocytes. Using mice that have severe combined immunodeficiency (scid) and mice lacking T cells (nude), we found that the absence of B cells can more seriously hamper the development and paring of adult worms, but granuloma formation of Schistosoma japonicum in scid mice was not down-regulated comparing with that in nude mice. The level of IL-10in the sera of nude mice was significantly higher than of scid mice at43days post infection (p.i.). Thus multiple mechanisms of immune modulation seem to be involved in parasite development and reproduction by helminth-induced regulatory B cells. Our findings have significance for understanding the molecular connections between schistosomes and T-and B-cells, indicating that more research is needed to develop efficient vaccine-based therapies for schistosomiasis.To understanrd the regulation mechanisms by B cells, especially Bregs, mediating parasite development, we have used the proper host lacking related immune cells, such as nude, scid mice, to study Bregs'role in adult worms development by means of determining their growth indicators, moreover, the monocytes, macrphages and dendritic cells are the predominant responders to pathogen-associated molecular patterns such as LPS and are the mediators of LPS on schistosome development. In Our research, LPS administration restores schistosome development in the condition of lacking T cells, but it is not if lacking T and B cells. It is an evidence in support of the hypothesis that B cells regulate the development of adult worms through the innate immune way by TGF-?.In addition, we have study the relations of Bregs and the cytokines IL-10and TGF-P to find the singal pathway of B cells regulating blood fluke development in the host innate immune by schistosome infection. Bregs may be induced by infection of S. japonium and release IL-10to balance inflammation factor in immune response. LPS stumilation does not induce and increase Bregs in spleen cells of nude mice.