The Roles of CD4+T Cells in Tumor Immunity

Abstract

Activation of CD8+cytotoxic T cells has long been regarded as a major antitumor mechanism of the immune system. Emerging evidence suggests that CD4+T cells are required for the generation and maintenance of effective CD8+cytotoxic and memory T cells, a phenomenon known as CD4+T-cell help. CD4+T-cell help facilitates the optimal expansion, trafficking, and effector function of CD8+T cells, thereby enhancing tumor destruction. In addition, a specialized subset of CD4+T cells, CD4+CD25+regulatory T cells (TRegs), effectively hampers anti-tumor immune responses, which has been proposed to be one of the major tumor immune evasion mechanisms. Here, we review recent advances in deciphering how anti-tumor immune responses are orchestrated by CD4+T cells. We will also discuss the immunotherapeutic potential of CD4+T-cell manipulation in anti-tumor immune response.