T-cell-mediated immune system

The term "T-cell-mediated immune system" refers collectively to all processes involving adaptive cellular immunity mediated by different types of T lymphocytes. This includes helper CD4+ T cells that orchestrate and regulate other immune responses through cytokine secretion and interaction with antigen-presenting cells. It also includes cytotoxic CD8+ T cells that directly kill infected or malignant host cells. Regulatory CD4+CD25+FOXP3+ regulatory T cells suppress excessive responses and prevent autoimmunity. The overall function is highly discriminative against intracellular pathogens such as viruses and certain bacteria but also plays roles in cancer surveillance and transplant rejection. The main molecular players include the diverse family of surface markers such as CD3/TCR complex for antigen recognition, co-receptors like CD4/CD8 for MHC-restricted activation/differentiation into effector subsets—Th1/Th2/Th17/Treg—and numerous cytokines involved in intercellular communication during an adaptive response. This broad category is not itself considered a single therapeutic target but instead encompasses many individual targets relevant across immunology research and therapy development.

Other names

Cell-mediated immunityCellular immunityT cell immunity

Suppression of T cell activation/proliferation by immunosuppressants; enhancement of antitumor activity by checkpoint inhibitors via blockade of inhibitory signals to cytotoxic T cells