Figure 2. Isolation and enrichment strategy of primary NK cells from human PBMC. (A) Experimental design of the NK cell enrichment strategy. PBMCs were collected from multiple donors (ages 20-42 years old), and NK cells were isolated and enriched. (B) Flow cytometry analysis of CD56 and CD16 expression in NK cells before and after enrichment for a representative donor. (B-i) Before enrichment, 1.64% of NK cells (0.18% of PBMCs) were CD56Bright CD16- and 46.34% of NK cells (2.8% of PBMCs) were CD56Dim CD16+ NK cells. (B-ii) After enrichment, 2.29% of NK cells (0.47% of PBMCs) were CD56Bright CD16- and 66.18% of NK cells (12.6% of PBMCs) were CD56Dim CD16+ NK cells. (C-i) Average percentage of CD56Dim CD16+ NK cell population in PBMCs from five donors. (C-ii) Average percentage of CD56Bright CD16- NK cell population in PBMCs from five donors. Donor sex and age are indicated in the figure. Statistical analysis performed using paired t test. *p < 0.05, **p < 0.01, and ***p < 0.001.