Human CD34+/dim neutrophil-committed progenitors do not differentiate into neutrophil-like CXCR1+CD14+CD16- monocytes in vitro

The advent of recent cutting-edge technologies has allowed the discovery and characterization of novel hematopoietic progenitors, including SSCloCD66b+CD15+CD11b-CD49dhiproNeu1s and SSChiCD66b+CD15+CD11b-CD49dintproNeus2s, CD66b+CD15+CD11b+CD49d+CD101-preNeus and Lin-CD66b+CD117+CD71+eNePs along human neutropoiesis process. In this research field, we recently identified CD66b-CD38+CD64dimCD115-, CD34+ and CD34dim/-cells exclusively committed to the neutrophil lineage [which we renamed as CD34+ and CD34dim/- neutrophil-committed progenitors (NCPs)], representing the earliest neutrophil precursors identifiable and sorted by flow cytometry. Moreover, based on their differential CD34 and CD45RA expression, we could identify four populations of NCPs, namely: CD34+CD45RA-/NCP1s, CD34+CD45RA+/NCP2s, CD34dim/-CD45RA+/NCP3s and CD34dim/-CD45RA-/NCP4s. This said, a very recent study by Ikeda and coworkers (PMID: 36862552) reported that neutrophil precursors termed either neutrophil progenitors (NePs) or “early neutrophil-committed progenitors” would generate immunosuppressive neutrophil-like CXCR1+CD14+CD16-monocytes. Hence, presuming that NePs/alias “early neutrophil-committed progenitors” correspond to NCPs, the selective neutrophil-commitment that we attributed to NCPs is contradicted by Ikeda and coworkers' paper. In this study, by performing a more analytical reevaluation at the phenotypic and molecular levels of the cells generated by NCP2s and NCP4s (selected as representatives of NCPs), we categorically exclude that NCPs generate neutrophil-like CXCR1+CD14+CD16-monocytes. Rather, we provide substantial evidence indicating that the cells generated by NePs/alias “early neutrophil-committed progenitors” are neutrophilic cells at different stage of maturation, displaying moderate levels of CD14, instead of neutrophil-like CXCR1+CD14+CD16-monocytes as pointed by Ikeda and coworkers. Hence, the conclusion that NePs/alias “early neutrophil-committed progenitors” aberrantly differentiate into neutrophil-like monocytes derives, in our opinion, from data misinterpretation Overall design: To assess their differentiation potential, sorted NCP2s (PMID: 35484408) were cultured on MS-5 stromal cell line (ACC 441, Leibniz-Institut DSMZ, Braunschweig, Germany), according to established protocols (PMID:26292072) • After 6 days in culture, CD66b+ cells generated by NCP2s cells were then prepared for RNA sequencing studies. The bulk RNA-seqs obtained were then compared with other retrieved from published studies: The bulk RNA-seqs obtained were then compared with others retrieved from published studies. • GSE113182: GSM3099240, GSM3099244 • GSE175880: GSM5772725, GSM5772727, GSM5772728, GSM5772729, GSM5772730, GSM5772731, GSM5772732, GSM5772733, GSM5772734, GSM5772735, GSM5772736, GSM5772737, GSM5772738, GSM5772739, GSM5772740, GSM5772741, GSM5772742, GSM5772743, GSM5772744, GSM5772747, GSM5772748, GSM5772749, GSM5772751, GSM5772752, GSM5772753, GSM5772756, GSM5772757, GSM5772758, GSM5772761, GSM5772762, and GSM5772763) • GSE136107: GSM4041235, GSM4041236, GSM4041237, GSM4041243, GSM4041244, GSM4041245, GSM4041246, GSM4041247, GSM4041248. • GSE224101: GSM7011869, GSM7011870, GSM7011871, GSM7011872, and GSM7011873)