title: Rapid Proliferation and Differentiation of a Subset of Circulating IgM Memory B Cells to a CpG/Cytokine Stimulus In Vitro.
abstract: Circulating human IgM expressing memory B cells have been incompletely characterized. Here, we compared the phenotype and in vitro functional response (capacity to proliferate and differentiate to antibody secreting cells) in response to CpG and a cytokine cocktail (IL-2, IL-6, and IL-10) of sorted naïve B cells, IgM memory B cells and isotype-switched circulating memory B cells. Compared to naïve B cells, IgM memory B cells had lower integrated mean fluorescence intensity (iMFI) of BAFF-R, CD38, CD73, and IL-21R, but higher iMFI of CD95, CD11c, TLR9, PD-1, and CD122. Compared to switched memory B cells, IgM memory B cells had higher iMFI of BAFF-R, PD-1, IL-21R, TLR9, and CD122, but lower iMFI of CD38, CD95, and CD73. Four days after receiving the CpG/cytokine cocktail, higher frequencies of IgM than switched memory B cells-and these in turn greater than naïve cells-proliferated and differentiated to antibody secreting cells. At this time point, a small percentage (median of 7.6%) of stimulated IgM memory B cells changed isotype to IgG. Thus, among the heterogeneous population of human circulating IgM memory B cells a subset is capable of a rapid functional response to a CpG/cytokine stimulus in vitro.
authors.affiliation: Instituto de Genética Humana, Facultad de Medicina, Pontificia Universidad Javeriana, Bogotá, Colombia.
authors.forename: Camilo
authors.initials: C
authors.lastname: Vásquez
authors.affiliation: Instituto de Genética Humana, Facultad de Medicina, Pontificia Universidad Javeriana, Bogotá, Colombia.
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Franco
authors.affiliation: Instituto de Genética Humana, Facultad de Medicina, Pontificia Universidad Javeriana, Bogotá, Colombia.
authors.forename: Juana
authors.initials: J
authors.lastname: Angel
mesh_terms: D016175:B-Lymphocyte Subsets / Q000166:cytology* / Q000187:drug effects / Q000276:immunology; D001402:B-Lymphocytes / Q000166:cytology* / Q000187:drug effects / Q000276:immunology; D002454:Cell Differentiation / Q000187:drug effects / Q000276:immunology*; D049109:Cell Proliferation / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D017578:Immunoglobulin Class Switching; D007075:Immunoglobulin M / Q000276:immunology*; D007156:Immunologic Memory / Q000187:drug effects / Q000276:immunology; D016753:Interleukin-10 / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology
chemical_list: D007075:Immunoglobulin M; D007376:Interleukin-2; D015850:Interleukin-6; D016753:Interleukin-10