Effect of Chlamydia trachomatis infection on the MHC class I and II molecules expression on HeLa cells

Objective To study the expression of MHC classⅠ molecules and MHC class Ⅱ molecules on HeLa cells infected with Chlamydia tr achomatis. Methods The immune fluorescence assay and fl ow cytometer assay were adopted to analyze the expression of MHC class Ⅰ molecu les and MHC class Ⅱ molecules induced by IFN-γ on the infected and uninfected HeLa cells. The antagonistic action of anti-IL-10 to IL-10 was assyed. Results The expression of MHC class Ⅰ and IFN-γ-induced MH C class Ⅱ molecules on C.trachomatis-infected HeLa cells were decreased wi th increasing dose of Ct and infection time. The differences mentioned above were all significant as compared with corresponding control cells(P0.01). IL-10 antibody inhibited partially the down-regulation of MHC class Ⅰ, but n ot IFN-γ-induced MHC class Ⅱ molecules expression, on infected HeLa cells. Conclusion The results suggest that Ct infection down -regulate MHC class Ⅰ molecules and IFN-γ-induced MHC class Ⅱ molecules e xpression on HeLa cells which may facilitate chlamydial persistence. The inhibit ion of MHC class Ⅰ, but not IFN-γ-induced MHC class Ⅱ molecules expression on HeLa cells infected with C.trachomatis is due, at least partially, to the IL-10 induced during C.trachomatis infection.