Increased frequencies of Th17 and Th22 cells in the peripheral blood of patients with secondary syphilis.

T-helper (Th) 17 and the more recently identified Th22 cells are of great importance in host defense against pathogens, but can also be responsible for chronic inflammatory disorders. However, the roles of the two cell subsets in syphilis remain elusive. In this study, we show that the frequencies of Th17 and Th22 cells are significantly increased in the peripheral blood of patients with secondary syphilis (SS). A significant positive correlation is observed between Th17 and Th22 cells, whereas a negative correlation exists between Th17 and Th1 cells. Moreover, the frequency of Th17 cells has a significant positive correlation with the plasma interleukin 6 (IL-6) or IL-1β levels, and the frequency of Th22 cells is positively correlated with the IL-6 or IL-23 levels. Finally, the elevated frequencies of Th17 and Th22 cells are positively associated with plasma C-reactive protein levels. Our results suggest that Th17 and Th22 cells may be implicated in the pathogenesis of the SS.