Helper inducer T cells, also known as CD4+ T cells or helper T cells, are a type of lymphocyte that plays a crucial role in the adaptive immune response. These cells express the CD4 protein on their surface, which allows them to interact with major histocompatibility complex class II (MHC-II) molecules on antigen-presenting cells (APCs), such as macrophages or dendritic cells.
The primary function of helper inducer T cells is to orchestrate immune responses by coordinating and regulating the activities of other immune cells, including B cells, cytotoxic T cells, and macrophages. They achieve this through the secretion of specific signaling molecules called cytokines. These cytokines help to stimulate and direct the immune response against pathogens such as viruses, bacteria, or parasites.
Helper inducer T cells can differentiate into distinct subsets of effector cells, known as Th1, Th2, Th17, and regulatory T cells (Tregs). Each subset has its unique cytokine profile and performs specific functions in the immune response.
Th1 cells primarily produce interferon-gamma (IFN-γ) and activate macrophages to enhance phagocytosis and kill intracellular pathogens. Th2 cells secrete cytokines like interleukin-4 (IL-4) and play a vital role in the antibody-mediated immune response, aiding B cells in producing specific antibodies. Th17 cells produce IL-17 and contribute to the immune response against extracellular bacteria and fungi.
Furthermore, regulatory T cells help maintain self-tolerance and prevent excessive immune responses that could lead to autoimmune diseases or allergies.
Overall, helper inducer T cells are essential in coordinating and modulating immune responses, ensuring an appropriate and effective defense against invading pathogens.
