[Recent research advances on function of CD4+T lymphocytes]

Cellular immunity is an important component of human immune system and plays a crucial role in the fight against tumor cell or invasive pathogens. Researches on cell-based immunotherapy have long been focused on eliciting tumor-specific CD8+ cytotoxic T lymphocytes (CTL) because of their potent killing activity and their ability to reject transplanted organs. However, the resulting treatments have been surprisingly poor at inducing complete tumor rejection, in both the experimental models and clinical trials. The CD4+ T cells has been studied mainly for their role as helpers for CD8+ CTL, even suggesting that the tumor-specific CD4 T regulatory cells could act as suppressors of antitumor responses. Recent studies indicated that CD4+T cells are not a pure cell lineage with single function, but a cell population with complex functions. Moreover CD4+ T cells may not only be helper cells, but also act as potent effector cells or partners with NK cells that can clear a wide variety of tumors. In a word, the antitumor potential of effector CD4+ T cells might have been underestimated. In this article, the classification and differentiation of CD4+ T cells, the function and secreted cytokines of CD4+ T cells, the CD4+ T cells and tumor immune, the tumor-immuno regulatory effects of CD4+ T cells, and clinical researches of CD4+ T cells are reviewed.