Standardized single‐platform assay for human monocyte subpopulations: Lower CD14 + CD16 ++ monocytes in females

We present a novel single‐platform assay for determination of the absolute number of human blood monocyte subpopulations, i.e., the CD14 ++ CD16 − and the CD14 + CD16 ++ monocytes. A four‐color combination of antibodies to CD14, CD16, CD45, and HLA‐DR reduces the spill‐over of natural killer cells and of granulocytes into the CD14 + CD16 ++ monocyte gate. For these CD14 + CD16 ++ monocytes, the intra‐assay coefficient of variation (CV) was 4.1% and the inter‐assay CV was 8.5%. Looking at a cohort of 40 donors aged 18–60 years, we found no age dependence. There was however an effect of gender in that females had lower CD14 + CD16 ++ monocytes (45.4 ± 13.5 cells/μl) compared with males (59.1 ± 20.3 cells/μl) ( P < 0.02). Using this novel approach, we can confirm that exercise will lead to more than three‐fold increase of the CD14 + CD16 ++ monocytes. Also, we show that therapy with low doses of glucocorticoids will deplete these cells. This robust single‐platform assay may be a useful tool for monitoring the absolute number of monocyte subpopulations in health and disease. © 2010 International Society for Advancement of Cytometry