Detection of under-expression of selected genes in NK cells is used to confirm a hypoxic tumor microenvironment that is ordinarily suppressive with respect to ADCC and cytotoxic cell killing of NK cells. Most notably, while hypoxia is known to upregulate HIF-1α and genes under the control of HIF-1α, hypoxia in a tumor microenvironment led to under-expression of selected genes, including HIF-1α. Thus, gene expression analysis of certain genes on NK cells can be used to detect conditions in a tumor that would indicate use of haNK cells.