Correlation of human CD56+ cell cytotoxicity and IFN-γ production

The use of an IFN-gamma ELISPOT assay to evaluate cellular immune responses has gained increasing popularity, especially as a surrogate measure for cytotoxic T lymphocyte (CTL) responses. We have compared the IFN-gamma ELISPOT assay and the traditional Cr-51 release assay for detection of human natural killer (NK) cell activity. The cell populations used for evaluation of these assays included freshly isolated and IL-2-activated peripheral blood mononuclear cells (PBMC), CD56-positive cells were demonstrated to be the primary source of the IFN-gamma signal when PBMC were evaluated with NK-sensitive targets in the IFN-gamma ELISPOT assay. IFN-gamma ELISPOT and Cr-51 release assays showed excellent correlation suggesting that NK activity can be reliably evaluated with methods other than the traditional Cr-51 release assays. (C) 2001 Academic Press.