Antigen presenting cells may be able to distinguish between normal and radiated Schistosoma japonicum cercaria： an in vitro observation

Objective： To observe the discrepancies of responses induced by Schistosoma japonicum （S. japonicum） normal cercaria antigen （NCA） and ultraviolet （UV） -radiation-attenuated cercaria antigen （UVACA） in an in vitro system. Methods： S. japonicum cercariae were collected and UVACA and NCA were prepared. Mouse macro- phage model cells （RAW 264.7） were treated with medium, NCA （40 μg/mL） or UVACA （40 μg/mL） in the presence or absence of recombinant mouse interferon gamma （rmIFN-γ; 4 ng/mL） for 48 h. Cell surface staining and flow cytometry were used to assess the major histocompatibility complex （MHC） Ⅱ expression, and data were expressed as mean fluorescence intensities （MFI）. Interleukin （IL） -10, IL-6 and prostaglandin E2 （PGE2） in cell culture supernatant were evaluated by commercial enzyme-linked immunosorbent assays. Results： NCA significantly suppressed IFN-7-induced MHC Ⅱ expression on RAW 264.7 cells. In the presence of 1FN-7, NCA significantly promoted IL-6, IL-10 and PGE2 secretion from RAW 264.7 cells. In the presence of IFN-γ, UVACA significantly promoted IL-10 but not IL-6 and PGE2 secretion from RAW 264.7 cells and showed no effect on IFN-γ-induced MHC Ⅱ expression. Compared with UVACA, NCA significantly suppressed IFN-γ-induced MHC Ⅱ expression and significantly promoted IL-6, PGE2 and IL-10 secretion from RAW 264.7 cells. Conclusion： RAW 264.7 cells respond differently to NCA and UVACA. NCA can significantly suppress IFN-γ-induced MHC Ⅱ expression and significantly promote IL-6, IL-10 and PGE2 secretion from RAW 264.7 cells compared with UVACA.