A new stable detection method of natural killer cell activity by flow cytometry

Objective To establish a new stable flow cytometric detection method for natural killer (NK) cell activity in human peripheral blood. Methods K562 target cell line with an enhanced green fluorescent protein (EGFP) stable expression was established by lentivirus-mediated transfection method. The AnnexinV-PE/7AAD double staining markers were used for apoptosis labeling, followed by a flow cytometric test. The percentage of apoptotic target cells reflected cytotoxic activity of NK cells. To verify this novel method, 43 adult healthy volunteers and 37 adult hemophagocytic syndrome (HPS) patients were selected for comparing the difference of NK cell activity between the two groups. Results There were no significant differences in gender (M/F 21∶22 vs. 21∶16, P= 0.479) and age [(30.53±7.13) y vs. (33.24±10.78) y, P= 0.198] between 43 healthy volunteers and 37 HPS patients, whereas the cytotoxic function of NK cells in HPS patients was significantly lower than that in health persons [(11.79±2.73) % vs. (21.08±4.26) %, P < 0.001]. Conclusion This detection method is rapid, accurate and stable, and it can be easily accomplished in most clinical laboratories, which provides a new approach to determine the cytotoxic activity of NK cells. Key words: NK cell activity; Flow cytometry; Peripheral blood; Apoptosis