Effect of age on absolute numbers of T and non-T lymphocytes.

Data from 120 healthy donors, 18-105 years of age, were plotted as individual data points. R and P values were calculated by linear regression analysis. (A) Absolute numbers of T lymphocytes (defined as CD3⁺, ▪) declined progressively with age, whereas non-T lymphocytes (defined as CD3⁻, □) remained unchanged. (B, C) The percentages and absolute numbers of circulating CD95⁻ (○) and CD95⁺ (•) cells among CD3⁺ T cells were calculated as described in “Materials and methods.” The percentages and absolute numbers of circulating CD95⁻ cells progressively decreased with age, whereas CD95⁺ cells increased only in percentages but did not significantly change in absolute numbers until the last decades of life.