title: Postnatal and adult immunoglobulin repertoires of innate-like CD19(+)CD45R(lo) B Cells.
abstract: The diversity in antibody repertoire relies on different B cell populations working efficiently to fulfil distinct specific functions. We recently described an innate-like CD19(+)CD45R(-/lo) (19(+)45R(lo)) cell population in postnatal unstimulated adult mice, a heterogeneous population containing cells expressing immunoglobulin M (IgM) and others behaving as differentiated mature B lymphocytes (intracytoplasmic IgG1, AID(+), Blimp-1(+)RAG2(-)). In the present study, we characterized the Ig repertoire expressed by splenic 19(+)45R(lo) cells, assuming that they would bear a restricted repertoire biased for germline rearrangements and low mutation rates similar to other innate-like cells. Sequences from 19(+)45R(lo) cells displayed a variety of V, D and J regions, and the analysis of the CDR-H3 region revealed an intermediate overall CDR-H3 length and moderate hydrophobicity. Both IgM and switched sequences of PD15 19(+)45R(lo) cells had shorter CDR-H3 region and fewer non-template N nucleotides than adult sequences, as expected for profiles that correspond to an immature phenotype. Regarding the mutation rate in the VH regions, IgG1 sequences already carried a high rate of replacement mutations at PD15, which increased further in the sequences obtained from adult mice. Moreover, statistical models suggest that a proportion of the switched sequences in adult 19(+)45R(lo) cells had experienced antigen selection, unlike other innate-like B cell compartments.
authors.affiliation: Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Prado
authors.forename: Mercedes
authors.initials: M
authors.lastname: Rodríguez
authors.forename: Isabel
authors.initials: I
authors.lastname: Cortegano
authors.forename: Carolina
authors.initials: C
authors.lastname: Ruiz
authors.forename: Mario
authors.initials: M
authors.lastname: Alía
authors.forename: Belén
authors.initials: B
authors.lastname: de Andrés
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Gaspar
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000916:Antibody Diversity / Q000235:genetics; D018941:Antigens, CD19 / Q000378:metabolism; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D007107:Immune System / Q000196:embryology / Q000254:growth & development*; D007113:Immunity, Innate / Q000235:genetics; D017578:Immunoglobulin Class Switching / Q000235:genetics; D007136:Immunoglobulins / Q000235:genetics*; D007156:Immunologic Memory; D017493:Leukocyte Common Antigens / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D060152:V(D)J Recombination / Q000235:genetics
chemical_list: D018941:Antigens, CD19; D007136:Immunoglobulins; D017493:Leukocyte Common Antigens