Helper T lymphocytes
What are Th cells?
T-helper cells (Th cells) are a subset of αβT-cells that usually express the CD4 co-receptor and have a major role in controlling and regulating the immune system by providing ‘help’ to other immune cells.
What is the role of Th cells in the immune system?
The cells are vital to human immune responses because they orchestrate the immune system by controlling other T-cell subsets, B-cells and innate immune responses. The Th cell response is defined by two distinct pathways involving two different subtypes of Th cell; Th1 and Th2 cells. Classically, Th1 cells are targeted towards intravesicular pathogens such as bacteria and parasites via the activation of infected macrophages, whilst Th2 cells invoke antibody production in B-cells, which neutralise extracellular pathogens and toxins. Th cell activation leads to the induction of a number of pathways that can result in B-cell antibody production and immunoglobulin class switching, and macrophage action via both direct interaction and through the release of soluble factors.