Interferon gamma (IFNγ) is an important multifunctional cytokine that is primarily secreted by activated T lymphocytes and natural killer (NK) cells, and is involved in the regulation of nearly all phases of immune and inflammatory responses, such as the activation, growth, and differentiation of T cells, B cells, macrophages. IFNγ is also involved in regulating inflammatory responses of several other cell types, including endothelial cells and fibroblasts. While IFNγ was originally characterized based upon its anti-viral activities, it has also been shown to inhibit the proliferation of a variety of cells. The Millipore human IFNγ ELISPOT Antibody Pair provides a sensitive and highly reliable method for the detection of IFNγ secreting cells at the single cell level.