César Collino

Standardized flow cytometry assay for identification of human monocytic heterogeneity and LRP1 expression in monocyte subpopulations: Decreased expression of this receptor in nonclassical monocytes

In this article, 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 the low‐density lipoprotein receptor‐related protein 1 (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 with those obtained by a well‐standardized flow cytometry assay based on the HLA‐DR monocyte‐gating strategy. We also demonstrated that 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.

Mycetoma of the scalp due to Microsporum canis: hystopathologic, mycologic, and immunogenetic features in a 6-year-old girl.

Dermatophytic mycetoma is an extremely rare subcutaneous mycosis. Here, we report the case of a 6-year-old girl with clinical, histologic, and mycologic findings consistent with a mycetoma of the scalp caused by Microsporum canis. To our knowledge, this is the first report showing the immunologic and immunogenetic features of a patient with a recalcitrant dermatophytic mycetoma.

Statistical Criteria to Establish Optimal Antibody Dilution in Flow Cytometry Analysis

In direct techniques of flow cytometry, the optimal antibody dilution or titer point is established from the plateau area of the antibody titration curve. However, the plateau area is defined without any statistical criteria, which may lead to an incorrect selection of antibody dilution. Herein, we report statistical criteria to establish the optimal antibody dilution for CD14, CD8, CD4, and CD3 analysis by flow cytometry in peripheral whole blood.