The influence of age,race, and gender on peripheral blood mononuclear-cell subsets in healthy nonsmokers

To investigate the influence of age, race, and gender on the cellular immune system, we determined T-cell, B-cell, monocyte, natural killer (NK)-cell, and HLA-DR⁺-cell subsets in 266 nonsmokers from a population-based random sample of healthy adults using monoclonal antibodies and flow cytometry. Blacks had a lower total white blood-cell count than whites (P0.0001), due primarily to a decrease in granulocytes. There was no significant difference in absolute lymphocyte count between blacks and whites. Blacks had a higher proportion of CD19⁺ cells (Leu 12⁺ B cells) and a lower proportion of CD3⁺ cells (OKT3⁺ T cells) than whites (P0.01). Female sex and increasing age were independently associated with an increased percentage of CD4⁺ cells (OKT4A⁺ helper-inducer T-cell subset), resulting in a higher helper/suppressor ratio among women and older individuals (P0.05). Black race and increasing age were independently associated with an increased proportion of HLA-DR⁺ cells (P0.0001) which was not attributable to B cells or monocytes. No significant age, race, or gender effects were observed for CD14⁺ cells (Leu M3⁺ monocytes) or CD16⁺ cells (Leu 11A⁺ natural killer cells). These data demonstrate that age, race, and gender are each associated with significant differences in peripheral blood monouclear-cell subsets. Population-based data such as these provide an important foundation for future design and interpretation of human flow cytometry data.