Furthermore, rSj16 could suppress inflammatory responses of the

host and inhibit the maturation of macrophages and dendritic cells (DCs) (8,9). It is known that the maturation status of DCs is crucial for the initiation of primary immune responses, and recently, it was confirmed that immature DCs are prone to induce regulatory T cells, which are a key components in maintaining immune homoeostasis and regulating immune responses in helminth infections (10–13). Although regulatory T cells were first described as differentiating in newborn thymus, it is now clear that they also develop in the periphery from nonregulatory T cells in a process termed ‘conversion’ (14). Some observations find more suggest that induction of regulatory T cells occurs during infections with certain pathogens, including Bordetella pertussis (15), the nematode Onchocerca volvulus (16), and schistosome infection. Some schistosoma antigens, such as HSP60 and S. japonicum egg antigens, have the ability to induce CD4+CD25+Foxp3+ regulatory T cells (17,18). Importantly, the immune click here response to the foreign antigens could cause inflammation to clear the pathogens, but there is little inflammation in the skin during an

schistosoma infection, which is a substantial protective response to benefit the parasite (19). However, the balance between proinflammatory and regulatory mechanisms following parasitic exposure is still unclear. In this study, we demonstrate that rSj16 can induce CD4+CD25+Foxp3+ regulatory T cells, and the immune suppression induced by these cells is dependent on IFN-γ and IL-10. Our study may provide some understanding of the mechanisms by

which cercariae escape antiparasite immune responses of the host. Recombinant Sj16 was produced as previously described (8). The protein was treated with AffinityPak Detoxi-Gel Endotoxin Removing Gel (Thermo, Barrington, USA) to remove endotoxin. To prepare soluble egg antigens (SEA), we followed the protocol as previously described (20). The concentration of rSj16 and SEA was determined by Bradford assay. Six- to 8-week-old female BALB/c and C57BL/6 mice Reverse transcriptase were purchased from Yangzhou University Mode Animal Center (Yangzhou, China). All animal experiments were performed in accordance with Chinese Animal Protection Laws and with permission from the Institutional Review Board. Mice in each of four experimental groups (six mice/group) were injected s.c. with 10 μg rSj16, SEA, OVA (Sigma, St. Louis, MO, USA) or PBS emulsified in incomplete Freund’s adjuvant (Sigma), respectively and boosted 2 weeks later with the antigens described earlier. Seven to 10 days after the last injection, animals were sacrificed, and the spleens were removed and homogenized in RPMI-1640 (Gibco, Guangzhou, China). The mouse femur bone marrow (BM) flushed with chilled RPMI-1640 medium to obtain BM cells. A single-cell suspension was formed by gently refluxing the expelled cell plug through a 25-gauge needle.