title: CD1high B cells: a population of mixed origin.
abstract: A specialized subpopulation of T lymphocytes is reactive to the MHC class I-like molecule CD1d. It is not clear which cells are the major antigen-presenting cells in vivo in the activation of CD1-restricted immune responses. We have characterized a subset of B lymphocytes expressing six- to eightfold higher levels of CD1 than the bulk of B cells. The cells have a surface phenotype (CD21(high), CD23(low), IgM(high), IgD(low)) found previously to characterize B cells residing in the splenic marginal zones. CD1(high) B cells localize preferentially to the spleen, and appear late in ontogeny, at 3 - 4 weeks of age. The CD1(high) B cells were present in mice lacking conventional helper T cells, ruling out an exclusive origin from T cell-dependent immune responses. Still, some CD1(high) B cells had been involved in T cell-dependent immune responses as suggested by mutations in their rearranged immunoglobulin gene regions. The population could still be found in mice with severely reduced B cell reactivity to bacterial lipopplysaccharides (C3H / HeJ mice) and in mice unable to respond to thymus-independent type 2 antigens (NFR.Xid mice), as well as in germ-free mice, indicating that bacterial antigens are not major stimuli for the induction of CD1(high) B cells. In contrast, the CD1(high) B cell population was severely reduced in CD19-deficient mice. Taken together, the results imply that the CD1(high) population is heterogenous and of mixed origin, dependent for its development or maintenance on signaling through the CD19 molecule.
authors.affiliation: Immunology Unit Department of Cell and Molecular Biology, Lund University, Lund, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Makowska
authors.forename: N N
authors.initials: NN
authors.lastname: Faizunnessa
authors.forename: P
authors.initials: P
authors.lastname: Anderson
authors.forename: T
authors.initials: T
authors.lastname: Midtvedt
authors.forename: S
authors.initials: S
authors.lastname: Cardell
mesh_terms: D000818:Animals; D018949:Antigens, CD1 / Q000032:analysis / Q000096:biosynthesis* / Q000276:immunology; D018941:Antigens, CD19 / Q000032:analysis / Q000276:immunology; D016175:B-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism*; D002999:Clone Cells / Q000276:immunology / Q000378:metabolism; D005434:Flow Cytometry; D007075:Immunoglobulin M / Q000032:analysis; D007136:Immunoglobulins / Q000235:genetics; D016130:Immunophenotyping; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D016688:Mice, Inbred NOD; D009154:Mutation / Q000235:genetics; D017464:Receptors, Complement 3d / Q000032:analysis; D017455:Receptors, IgE / Q000032:analysis; D013154:Spleen; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology
chemical_list: D018949:Antigens, CD1; D018941:Antigens, CD19; D007075:Immunoglobulin M; D007136:Immunoglobulins; D017464:Receptors, Complement 3d; D017455:Receptors, IgE