GFP-PH–mediated PIP2 masking impairs NK-cell cytotoxic function. Primary cultured NK cells were left uninfected or were infected with recombinant lentiviruses encoding GFP or GFP-PH constructs. Three days after infection, cells were assessed in a 51Cr release assay against P815 target cells (top) in the presence of anti-MHC class I (ctr), anti-CD16, anti-NKp46, or anti-2B4 mAb. One representative experiment of 5 performed is shown. Differences between GFP-PH group and NI or GFP-ctr groups in 5 independent experiments at all E:T ratios were significant. (Bottom) The same cell populations were stimulated with plastic-immobilized mAbs, as indicated, or PMA plus ionomycin. After 4 hours, cell supernatants were collected and assessed for BLT esterase release. Data represent the percentage (mean ± SD) of specific release (sample/total release) from 3 independent experiments. Differences between GFP-PH group and NI or GFP-ctr groups were significant (*P < .003).
