Phenotypic and biological characterization of human NK cells in PBMCs

Objective:To characterize the phenotypic and biological properties of NK cells in human PBMCs.Methods:PBMCs were isolated from normal individuals. Surface markers and intracellular cytotoxic molecules of PBMCs were stained with multi-color-labeled monoclonal antibodies and analyzed at the single cell level the relation between NK subsets and biological characterization by flow cytometer.Results:Three distinct subpopulations(CD56+,CD56+CD16+ and CD16+) of human NK cells could be identified based upon the expression of CD56 and CD16 molecules. All of CD56+ NK cells expressed CD95 but some of them revealed CD95 bright and CD95 dim.5%-6% of CD56+NK cells were CD8+;43.5% of CD95 bright and CD8+ subsets expressed Granzyme B and Perforin,whereas 1%-6% of other subsets were positive for Granzyme B and Perforin. CD56+CD16+ and CD16+ subsets were CD95 bright,whereas 32.2% of them were CD8+.Both CD56+CD16+ and CD16+ subsets expressed Granzyme B and Perforin were 83.6% and 89.8%,respectively,but 7.35% of CD56+CD16+ subset was negative for both Granzyme B and Perforin.Conclusion:NK cells in PBMCs are phenotypically and biologically heterogenous.With the reduction in the expression of CD56 and the increase in the expression of CD16 molecules,NK cells are gradually becoming maturation of biological properties.