The use of an IFN-gamma ELISPOT assay to evaluate cellular immune responses
has gained increasing popularity, especially as a surrogate measure for cy
totoxic T lymphocyte (CTL) responses. We have compared the IFN-gamma ELISPO
T assay and the traditional Cr-51 release assay for detection of human natu
ral 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 p
rimary source of the IFN-gamma signal when PBMC were evaluated with NK-sens
itive targets in the IFN-gamma ELISPOT assay. IFN-gamma ELISPOT and Cr-51 r
elease 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.