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

Objective: To study the expression of MHC class I molecules and MHC class II molecules on HeLa cells infected with Chlamydia trachomatis. Methods: The immune fluorescence assay and flow cytometer assay were adopted to analyze the expression of MHC class I molecules 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 MHC class II molecules on C. trachomatis-infected HeLa cells were decreased with increasing dose of Ct and infection time. The differences mentioned above were all significant as compared with corresponding control cells (P < 0.01). IL-10 antibody inhibited partially the down-regulation of MHC class I, but not 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 expression on HeLa cells which may facilitate chlamydial persistence. The inhibition 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.