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. 2011 Feb 10;2:10. doi: 10.3389/fmicb.2011.00010

Figure 5.

Figure 5

CD3−CD56+ natural killer (NK) cells are a major source of IFNγ in response to EB stimulation that increases with age. PBMC from healthy individuals ranging in age from 2 to 5 years (n = 5), 15–25 years (n = 5), and >35 years (n = 5) were stimulated for 24 h with EB. (A) Representative FACS plots demonstrate the gating strategy used to define populations of CD4+ and CD8+ T cells and NK cells. NK cells (CD3−CD56+) were gated from CD3+ T cells. The CD3+ T cells were then further sub-divided based on CD4+ or CD8+ expression. (B) Cell percentages in each age group demonstrate the natural variation of CD8+ T and NK cell levels, whereas CD4+ T cell levels do not appear to vary with age. (C) The percentage of NK cells producing IFNγ significantly increased with age, while the percentage of CD8+ IFNγ+ cells significantly decreased in the >35 years age group. The percentage of CD4+ IFNγ+ did not differ among the different age groups. (D) The percentage of CD107a+ NK cells significantly increased with age, whereas levels of CD107a expression in CD8+ T cells did not differ with age. CD4+ T cells expressed negligible levels of CD107a.