title: The majority of human memory B cells recognizing RhD and tetanus resides in IgM+ B cells.
abstract: B cell memory to T cell-dependent (TD) Ags are considered to largely reside in class-switched CD27(+) cells. However, we previously observed that anti-RhD (D) Igs cloned from two donors, hyperimmunized with D(+) erythrocytes, were predominantly of the IgM isotype. We therefore analyzed in this study the phenotype and frequency of D- and tetanus toxoid-specific B cells by culturing B cells in limiting dilution upon irradiated CD40L-expressing EL4.B5 cells and testing the culture supernatant. Most Ag-specific B cells for both TD Ags were found to reside in the IgM-expressing B cells, including CD27(-) B cells, in both hyperimmunized donors and nonhyperimmunized volunteers. Only shortly after immunization a sharp increase in Ag-specific CD27(+)IgG(+) B cells was observed. Next, B cells were enriched with D(+) erythrocyte ghosts and sorted as single cells. Sequencing of IGHV, IGLV, IGKV, and BCL6 genes from these D-specific B cell clones demonstrated that both CD27(-)IgM(+) and CD27(+)IgM(+) B cells harbored somatic mutations, documenting their Ag-selected nature. Furthermore, sequencing revealed a clonal relationship between the CD27(-)IgM(+), CD27(+)IgM(+), and CD27(+)IgG(+) B cell subsets. These data strongly support the recently described multiple layers of memory B cells to TD Ags in mice, where IgM(+) B cells represent a memory reservoir which can re-enter the germinal center and ensure replenishment of class-switched memory CD27(+) B cells from Ag-experienced precursors.
authors: Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands; and.
authors: Luciana
authors: L
authors: Della Valle
authors: Department of Internal Medicine, BovenIJ Hospital, 1034 CS Amsterdam, the Netherlands.
authors: Serge E
authors: SE
authors: Dohmen
authors: Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands; and.
authors: Onno J H M
authors: OJ
authors: Verhagen
authors: Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands; and.
authors: Magdalena A
authors: MA
authors: Berkowska
authors: Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands; and.
authors: Gestur
authors: G
authors: Vidarsson
authors: Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands; and e.vanderschoot@sanquin.nl.
authors: C
authors: C
authors: Ellen van der Schoot
mesh_terms: D000818:Animals; D016175:B-Lymphocyte Subsets / Q000145:classification / Q000276:immunology* / Q000378:metabolism*; D000939:Epitopes / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D018858:Germinal Center / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D006801:Humans; D017578:Immunoglobulin Class Switching / Q000235:genetics; D007072:Immunoglobulin D / Q000096:biosynthesis / Q000235:genetics; D007075:Immunoglobulin M / Q000096:biosynthesis* / Q000235:genetics; D007156:Immunologic Memory / Q000235:genetics; D016130:Immunophenotyping; D018655:Lymphocyte Count; D051379:Mice; D061251:Primary Cell Culture; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism; D013745:Tetanus Toxoid / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000939:Epitopes; D007072:Immunoglobulin D; D007075:Immunoglobulin M; D011993:Recombinant Fusion Proteins; C117760:RhD fusion protein, human; D013745:Tetanus Toxoid; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; C105243:RHOD protein, human; D020741:rho GTP-Binding Proteins