title: Characterization of a B220+ lymphoid cell subpopulation with immune modulatory functions in nasal-associated lymphoid tissues.
abstract: Complex mechanisms operate on mucosal tissues to regulate immune responsiveness and tolerance. When the lymphocyte subpopulations from murine nasal-associated lymphoid tissues (NALT) were characterized, we observed an accumulation of B220(low)CD3(low)CD4(-)CD8(-)CD19(-)c-Kit(+) cells. TCR transgenic mice and athymic mice were used for monitoring T cell lineage and the presence of extrathymic T cell precursors. The majority of cells from NALT exhibited a T cell precursor phenotype (CD4(-)CD8(-)CD19(-)c-Kit(+)). Fas-independent apoptosis was their main mechanism of cell death. We also demonstrated that B220(low)CD4(-)CD8(-)CD19(-) cells from NALT exhibited the potential to down-regulate the activation of mature T cells. However, the innate immunity receptor TLR2 was also highly expressed by this cell subpopulation. Moreover, nasal stimulation with a TLR2/6 agonist resulted in a partial activation of the double-negative cells. These results suggest that the immune responses in NALT may be in part modulated by a cell subpopulation that maintains a tolerogenic milieu by its proapoptotic status and suppressive activity, which can be reverted through stimulation of a TLR signaling cascade.
authors.affiliation: Division of Microbiology, GBF-German Research Center for Biotechnology, Braunschweig, Germany.
authors.forename: Faiza
authors.initials: F
authors.lastname: Rharbaoui
authors.forename: Dunja
authors.initials: D
authors.lastname: Bruder
authors.forename: Melita
authors.initials: M
authors.lastname: Vidakovic
authors.forename: Thomas
authors.initials: T
authors.lastname: Ebensen
authors.forename: Jan
authors.initials: J
authors.lastname: Buer
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Guzmán
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D017252:CD3 Complex / Q000096:biosynthesis; D015704:CD4 Antigens / Q000378:metabolism; D016827:CD8 Antigens / Q000378:metabolism; D002454:Cell Differentiation / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000378:metabolism; D007111:Immunity, Cellular / Q000502:physiology; D016130:Immunophenotyping; D017493:Leukocyte Common Antigens / Q000096:biosynthesis*; D008213:Lymphocyte Activation / Q000276:immunology; D016131:Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism; D008221:Lymphoid Tissue / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D019463:Mice, Inbred MRL lpr; D008819:Mice, Nude; D008822:Mice, Transgenic; D009297:Nasal Mucosa / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000502:physiology; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D051195:Toll-Like Receptor 2; D051193:Toll-Like Receptors; D019014:fas Receptor / Q000502:physiology
chemical_list: D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D051195:Toll-Like Receptor 2; D051193:Toll-Like Receptors; D019014:fas Receptor; D017493:Leukocyte Common Antigens