FluoroSpot Path: TB (ESAT‑6+CFP‑10+EspC) Human IFN‑γ/IL‑2

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.

Interleukin 2 (IL-2) is predominantly produced by activated T cells. IL-2 promotes the proliferation, differentiation, and survival of antigen-activated T cells and NK cells. After antigen stimulation, the cytokine also promotes the differentiation of T cells into effector and memory T cells. Therefore IL-2 plays an important role in the body's response to infection. IL-2 is also key to tolerance, as it promotes the differentiation of certain immature T cells into regulatory T cells in the thymus, ultimately preventing autoimmune diseases.