LFA-1 molecule is a marker of NK cell differentiation. (A) Flow cytometry analysis of LFA-1 expression on CD161⁺CD56⁺CD117⁺CD94/NKG2A⁻ (light gray line, empty profile), CD161⁺CD56⁺CD117^lowCD94/NKG2A⁺ (bold black line, empty profile), CD161⁺CD56⁺CD117⁻CD94/NKG2A⁺ (gray profile) cells. (B) After 20 days of culture, in vitro derived NK cells were analyzed for the expression of activating receptors gating separately on CD161⁺CD56⁺LFA-1⁻ cells (gray line, gray profile) or CD161⁺CD56⁺LFA-1⁺ cells (black line, empty profile). Dashed line in histograms indicates isotype control. (C) CD161⁺CD56⁺LFA-1⁻ immNK cells and CD161⁺CD56⁺LFA-1⁺ difNK cells were isolated by cell sorting and analyzed for their cytotoxic activity in a 4-hour ⁵¹Cr release assay against melanoma FO1 cell line. The E/T ratio was 5/1.