Standardized Flow Cytometry Assay for Identification of Human Monocytic Heterogeneity and LRP1 Expression in Monocyte Subpopulations: Decreased Expression of This Receptor in Nonclassical Monocytes

FERRER DARIO G.; JALDIN-FINCATI JAVIER; AMIGONE J.; CAPRA R.; COLLINO C; ALBERTINI R.; CHIABRANDO GUSTAVO

CYTOMETRY PART A

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2014 vol. 85 p. 601 - 610

1552-4922

We present a flow cytometry assay by which human blood monocyte subpopulations -classical (CD14++CD16-), intermediate (CD14++CD16+) and nonclassical (CD14+CD16++) monocytes - can be determined. Monocytic cells were selected from CD45+ leukocyte subsets by differential staining of LRP1, which allows reducing the spill-over of natural killer cells and granulocytes into the CD16+ monocyte gate. Percentages of monocyte subpopulations established by this procedure were significantly comparable to those obtained by a well standardized flow cytometry assay based on the HLA-DR monocyte-gating strategy. We also demonstrated that low density lipoprotein receptor-related protein 1 (LRP1) is differentially expressed at cell surface of monocyte subpopulations, being significantly lower in nonclassical monocytes than in classical and intermediate monocytes. Cell surface expression of LRP1 accounts for only 20% of the total cellular content in each monocyte subpopulation. Finally, we established the within-individual biological variation (bCV%) of circulating monocyte subpopulations in healthy donors, obtaining values of 21%, 20%, and 17% for nonclassical, intermediate and classical monocytes, respectively. Similar values of bCV% for LRP1 measured in each monocyte subpopulation were also obtained, suggesting that its variability is mainly influenced by the intrinsic biological variation of circulating monocytes. Thus, we conclude that LRP1 can be used as a third pan-monocytic marker together with CD14 and CD16 to properly identify monocyte subpopulations. The combined determination of monocyte subpopulations and LRP1 monocytic expression may be relevant for clinical studies of inflammatory processes, with special interest in atherosclerosis and cardiovascular disease.