Single cell transcriptomic profiling of human CD19+ B cells enriched for CD5+ Innate-like B cells

Aryl hydrocarbon receptor is a ligand-activated transcription factor whose activation can regulate B cell-mediated immune responses. Given the diverse nature of human B cell subsets, scRNA-seq transcriptomic profiling was used to ascertain the heterogeneity of AHR expression in discrete B cell subpopulations. We identified a unique cell cluster enriched in expression of AHR and CD9. Further, these cells were diminished in their expression of canonical B cell-associated genes and enriched with a myeloid cell-specified gene signature. These results were confirmed in vitro as CD14 expressing B cells were readily detectable in human donor PBMC and expressed significantly more AHR protein. Following activation in vitro, CD9+ B cells secreted IgM, IL-10, TGFß1, and several myeloid-associated pro-inflammatory mediators, specifically CXCL8. These results demonstrate CD14 expression by B cells is readily detectable in healthy human donors and their release of CXCL8 could implicate these cells in inflammatory diseases and autoimmunity. Overall design: PBMC were isolated by ficoll density gradient from 2 anonymous platelet donor leukapheresis packs naïve B cells were isolated by magnetic assisted cell sorting via negative selection. CD5 expressing B cells were enriched by positive selection for CD5 protein and then added back into a 1:1 ratio with CD5 negative B cells. RNA was extracted and then libraries were prepared using the 10X Genomics Chromium Single Cell 3' v3 kit and Chromium i7 Multiplex Kit.