FluoroSpot Plus: Human IFN‑γ/IL‑22/IL‑17A

Interferon-γ (IFN-γ) is the only type II interferon. This proinflammatory cytokine is secreted by activated T cells and NK cells. It activates macrophages and endothelial cells and regulates immune responses by affecting APCs, T cells, and B cells. Production of IFN-γ by helper T cells and cytotoxic T cells is a hallmark of the Th1-type phenotype. Thus, high-level production of IFN-γ is typically associated with effective host defense against intracellular pathogens.

The cytokine interleukin 22 (IL-22) is mainly produced by activated CD4 T helper 17 (Th17) and T helper 22 (Th22) cells. The IL-22 receptor is expressed on non-immune cells, particularly epithelial cells and keratinocytes, and IL-22 promotes innate immune responses versus bacterial infections in these target cells. In addition, Th22 cells have been shown to play a role in the pathophysiology of several human skin diseases.

Interleukin 17A (IL-17A) is a potent proinflammatory cytokine produced by activated Th17 (T helper 17) cells and certain cells belonging to the innate immune system. In mice, IL-17 has also been shown to be produced by activated CD8 T cells and γδ T cells. Th17 cells play an important role in autoimmune diseases and protection against bacteria and fungi. IL-17A acts on a broad range of cell types to induce the expression of cytokines, chemokines, and metalloproteinases. As a result, secretion of IL-17A promotes inflammatory responses, which leads to the recruitment of neutrophils, enhancement of antibody production, and activation of T cells. Increased expression of IL-17A is seen in autoimmune diseases such as multiple sclerosis and rheumatoid arthritis. It is also associated with asthma, psoriasis, cancer, and transplant rejection.