Changes in the receptor expression patterns of NK cells following expansion. (A) The surface expression levels of different receptors on day-0 and day-20 NK cells (CD3⁻CD56⁺) from all patients were assessed by multicolor flow cytometry as specified. For each receptor, analysis was made on receptor-positive subsets within the total NK-cell population. Representative data (patient 5) showing comparative phenotyping of day-0 (gray) and day-20 (white) cells. (B) Each patient's day-20/day-0 MFI ratios (○) for the cell surface receptors analyzed and the median values (—) are shown. The dashed line shows MFI ratio = 1.