CD4-positive T lymphocyte (CD4+ T cell)

CD4-positive T lymphocytes, often referred to as helper T cells, are a critical subset of white blood cells that play a central role in orchestrating the adaptive immune response. They recognize peptides presented by Major Histocompatibility Complex (MHC) class II molecules via their T-cell receptors (TCR) and differentiate into various effector subsets (such as Th1, Th2, Th17, and Treg) to direct the immune system's response to pathogens or self-antigens. In many autoimmune diseases, CD4-reactive T cells become pathologically activated against host tissues, making them primary targets for immunosuppressive and immunomodulatory therapies. Conversely, in oncology, these cells are harnessed or targeted to enhance anti-tumor immunity, while in HIV infection, their depletion is the hallmark of disease progression. Therapeutic strategies include direct depletion using monoclonal antibodies, inhibition of activation pathways, or the use of engineered CAR-T cells to redirect their specificity.

Other names

Helper T cellCD4-reactive T cellT-helper cellCD4+ T lymphocyteMHC class II-restricted T cell

Drugs targeting these cells typically act by inhibiting T-cell receptor signaling, blocking co-stimulatory signals (e.g., CTLA-4 Ig), depleting the cell population via antibody-dependent cellular cytotoxicity (ADCC), or preventing their migration into inflamed tissues (e.g., alpha-4 integrin blockade).