Cytokines are the hormonal messengers responsible for most of
the biological effects in the immune system, such as cell-
mediated immunity and allergic type responses. T lymphocytes are
a major source of cytokines. These cells bear antigen-specific
receptors on their cell surface to allow recognition of foreign
pathogens. There are two main subsets of T lymphocytes,
distinguished by the presence of cell surface molecules known as
CD4 and CD8. T lymphocytes expressing CD4 are also known as
helper T cells, and these are regarded as being the most
prolific cytokine producers. This subset can be further
subdivided into Th1 and Th2, and the cytokines they produce are
known as Th1-type cytokines and Th2-type cytokines. - Th1 cells
Type 1 helper T cells are characterized by the production of
pro-inflammatory cytokines like IFN-γ, IL-2, and TNF-β. Th1
cells are involved in cell-mediated immunity. The cytokines
produced by Th1 cells stimulate the phagocytosis and destruction
of microbial pathogens. Several chronic infl