Interleukin 22-producing CD4+ T cells in malignant pleural effusion.

Th22 cells have been reported to be involved in human cancers. However, differentiation and immune regulation of Th22 cells in malignant pleural effusion (MPE) remain unknown. We noted that Th22 cell numbers were increased in MPE, and that IL-22 substantially promoted the proliferation and migratory activity of A549 cells. Moreover, IL-22 could strongly facilitate intercellular adhesion of A549 cells to pleural mesothelial cell monolayers. Our data revealed that the increase in Th22 cells in MPE was due to pleural cytokines and chemokines, and that Th22 exerted an important immune regulation on cancer cells in human pleural malignant environment.