Correlation of Human CD56+ Cell Cytotoxicity and IFN-γ Production

The use of an IFN-γ 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-γ ELISPOT assay and the traditional 51Cr 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-γ signal when PBMC were evaluated with NK-sensitive targets in the IFN-γ ELISPOT assay. IFN-γ ELISPOT and 51Cr release assays showed excellent correlation suggesting that NK activity can be reliably evaluated with methods other than the traditional 51Cr release assays. © 2001 Academic Press