Th1 cytokines

Th1 cytokines are the cytokines interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-α), interleukin 2 (IL-2) and interleukin 12. Th1 cells are T-lymphocytes that predominantly secrete interferon-gamma.

The defense mechanisms of the immune system are divided into an innate (natural) immune response directed against all agents recognized as foreign to the body and an acquired (adaptive) one, in which antigen-specific cells and antibodies are produced against specific allergens / antigens / pathogens. In both systems, complex, interacting and regulating cell populations are active and dependent on the type and structure of the antigens. Both defense systems have cellular and humoral components.

The type of response with which the immune system reacts to an antigen is influenced by various activating and inhibiting factors. Thus, by the type and amount of antigen, by the specifics of the lesional tissue (epidermis, respiratory tract, gastrointestinal tract, the type of antigen presentation, and by the cytokine pattern expressed.

Antigen-presenting cells (APC), as well as other effector cells of the immune response, are responsible for the cytokine pattern that shapes an adequate immune response. These stimulate and shape different T cell subpopulations and thus their (specific) cytokine responses.

The Th1 - immune response is characterized by a cellular immune response through the cytokines: IF-gamma, TNF- -alpha, IL- 2 and IL-12. IL-12 and IF-gamma promote the development of Th1 cells via the activation of the transcription factors STAT4 and STAT1.

INF-gamma, in turn, activates macrophages, inhibits B cells, and thus prevents a Th2 response. Macrophages promote type 1 polarization of reactive T cells through their cytokine release (IL-12; TNF-alpha) as well as NO production. At the same time, macrophages intensify their action as antigen-presenting cells (APC) and enhance their antimicrobial ability against extracellular and intracellular antigens.

Thus, Th1 cells are considered the most important promoters of the cellular type immune response (delayed type hyersensitivity).Th1 responses also serve as tumor defense.

CD8-positive T cells are also involved in inhibiting the spread of disease triggers (pathogens). Through their release of IFN-gamma and direct cytotoxicity, they contribute to the overall cytotoxic potential of the Th1 immune response. At the same time, a type2 response is inhibited by the cytokines secreted. Th2 cells and their cytokine interleukin-4 in turn, are the major antagonists of the Th1 response.

In organ-related autoimmune diseases, there is often an immune imbalance in favor of Th1 cells. The excess of Th1 cells mediates and maintains a chronic inflammatory state.

The ratio of Th1 and Th2 cells can vary according to the current defense situation, but in healthy individuals it is balanced and readjusts even after activation of the immune system.