Generation of B and plasma cells involves several organs with a necessary cell trafficking between them. A detailed phenotypic characterization of four circulating B-cell subsets (immature-, naïve-, memory-B-lymphocytes and plasma cells) of 106 healthy adults was realized by multiparametric flow cytometry. We show that CD10, CD27 and CD38 is the minimal combination of subsetting markers allowing unequivocal identification of immature (CD10 IntroductionHuman B-cell biology has been extensively documented. CD38-memory B cells. Very low numbers of plasma cells (2/mL) are found in peripheral blood of healthy donors. Because of their low count, only few studies have been devoted to characterizing their phenotype, most of them dealing with newly generated plasma cells after in vivo immunization.2 Steady-state circulating plasma cells lack CD20, express CD19 and CD38 high . It has been recently reported that steady-state circulating plasma cells are mainly of mucosal origin, the majority of them secreting IgA (84%), expressing CCR10 (56%) and β7 integrin (32%).3 Steady-state circulating plasma cells are generally termed plasmablasts because only half express CD138, a proteoglycan that is a hallmark of plasma cells, 4 while they are CD45 + and HLA-class II + . Plasmablasts are generated in the lymph nodes, and induced to circulate for a short period until they will reach a niche in bone marrow, spleen, mucosa associated lymphoid tissues (MALT) or lymph nodes.5 These niches will provide circulating early plasma cells with those factors required to survive and to further differentiate into long-living mature plasma cells.1 In murine bone marrow, plasma cell niche involves SDF-1 producing cells and is shared with hematopoietic stem cells

No abstract

No abstract

No abstract