IFNγ is type II interferon produced by lymphocytes (T-cells, NK cells, NKT cells) in response to viral infections and inflammatory stimuli, including but not limited to bacterial lipopolysaccharide LPS and CpG DNA. Factors mitogenic to T-cells (e.g. PHA-M) can also induce this interferon. IFNγ is essential in maintaining function of adaptive immunity through regulation of T cell function. It is also important for protection from intracellular bacteria (e.g. M.tuberculosis) and anti-tumor immunity. This document describes experimental procedure for analysis of culture supernatants by ELISA to detect presence of IFNγ. NCL protocol ITA-10 should be referred to for details of preparation of culture supernatants.