CD4THelferTZellen

CD4THelferTZellen, the German-language term for CD4+ T helper cells, are a subset of T lymphocytes in the adaptive immune system. They express the CD4 glycoprotein and recognize peptide antigens presented by MHC class II molecules on professional antigen-presenting cells. CD4+ T helper cells play a central role in orchestrating immune responses by activating and regulating other immune cells, including B cells, cytotoxic T cells, and macrophages. They help determine the type of immune response through cytokine secretion and cell–cell interactions.

Development and subsets: They develop in the thymus and mature in the periphery; upon antigen recognition with co-stimulatory signals, they differentiate into distinct effector lineages. The main subsets include Th1, Th2, Th17, T follicular helper (Tfh), and regulatory T cells (Treg). Each subset is defined by characteristic cytokines and functions: Th1 (IFN-γ, IL-2) supports cell-mediated immunity; Th2 (IL-4, IL-5, IL-13) supports humoral responses; Th17 (IL-17) contributes to neutrophil recruitment; Tfh (IL-21) helps B cells in germinal centers; Treg (FoxP3, IL-10, TGF-β) suppresses immune responses to maintain tolerance.

Clinical relevance: CD4+ T cells are a primary target of human immunodeficiency virus (HIV), and the CD4 count is a key marker of immune status in HIV infection. In healthy adults, CD4+ T cell counts typically range from about 500 to 1,600 cells per microliter of blood. Antiretroviral therapy can restore CD4+ T cell numbers and function. Abnormal CD4+ T cell responses are involved in various autoimmune diseases and allergies.