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) nor-mal 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 stain-ing 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-γ-induced MHCⅡ expression on RAW 264.7 cells. In the presence of IFN-γ, 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.