The slan antigen identifies the prototypical non-classical CD16+-monocytes in human blood [scRNA-seq]

Peripheral monocytes in humans are conventionally divided into classical (CL, CD14++CD16−), intermediate (INT, CD14++CD16+) and non-classical (NC, CD14dim/−CD16++) cells, based on their expression levels of CD14 and CD16. A major fraction of the NC-monocytes has been shown to express the 6-sulfo LacNAc (slan) antigen, but whether these slan+/NC-monocytes represent the prototypic non-classical monocytes or whether they are simply a sub-fraction with identical features as the remainder of NC monocytes is still unclear. Unsupervised clustering of scRNAseq data generated one cluster of NC- and one of INT-monocytes, where all slan+/NC-monocytes were allocated to the NC-monocyte cluster, while slan−/NC-monocytes were found, in part (13.38 %), within the INT-monocyte cluster. In addition, total NC- and slan−/NC-monocytes, but not slan+/NC-monocytes, were found to contain a small percentage of natural killer cells. Altogether, this data prove that slan+/NC-, but not slan−/NC-, monocytes are more representative of prototypical NC-monocytes. Monocytes subsets were isolated by Fluorescence-activated cell sorting (FACS) according to the presence or absence of CD14, CD16 and slan membrane markers and analyzed using scRNA-seq