Human Germinal Center B Cells Differ from Naïve and Memory B Cells in CD40 Expression and CD40L-Induced Signaling Response.
CYTOMETRY PART A(2019)
摘要
CD40 expression is required for germinal center (GC) formation and function, but the kinetics and magnitude of signaling following CD40 engagement remain poorly characterized in human B cells undergoing GC reactions. Here, differences in CD40 expression and signaling responses were compared across differentiation stages of mature human tonsillar B cells. A combination of mass cytometry and phospho-specific flow cytometry was used to quantify protein expression and CD40L-induced signaling in primary human naive, GC, and memory B cells. Protein expression signatures of cell subsets were quantified using viSNE and Marker Enrichment Modeling (MEM). This approach revealed enriched expression of CD40 protein in GC B cells, compared to naive and memory B cells. Despite this, GC B cells responded to CD40L engagement with lower phosphorylation of NF kappa B p65 during the first 30 min following CD40L activation. Before CD40L stimulation, GC B cells expressed higher levels of suppressor protein I kappa B alpha than naive and memory B cells. Following CD40 activation, I kappa B alpha was rapidly degraded and reached equivalently low levels in naive, GC, and memory B cells at 30 min following CD40L. Quantifying CD40 signaling responses as a function of bound ligand revealed a correlation between bound CD40L and degree of induced NF kappa B p65 phosphorylation, whereas comparable I kappa B alpha degradation occurred at all measured levels of CD40L binding. These results characterize cell-intrinsic signaling differences that exist in mature human B cells undergoing GC reactions. (c) 2019 International Society for Advancement of Cytometry
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关键词
CD40 signaling,phospho-flow,mass cytometry,germinal center B cells,human tonsils
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