title: B cell activation regulates exosomal HLA production.
abstract: Exosomes are nanovesicles produced constitutively and inducibly by several types of cells. They are generated as intraluminal vesicles of multivesicular bodies and express MHC and several endosomal/lysosomal proteins. In spite of their potential role in cellular immunity, the regulatory mechanisms of exosome production are largely unknown. In this study, we have established a novel ELISA system to quantify exosomal HLA using a combination of anti-HLA class I and anti-HLA-DR mAb. We found that exosomal HLA production of B cells was enhanced by contact with CD4(+) T cells. Neutralizing anti-CD154 (CD40L) mAb inhibited this effect, and a soluble CD40L significantly increased production of exosomal HLA in B cells. In addition, B cell stimulation via BCR and TLR9 enhanced their production while IL-4 stimulation alone failed to do so. Strikingly, an inhibitor of the classical NF-kappaB pathway drastically inhibited exosomal HLA production in stimulated B cells, indicating that the classical NF-kappaB pathway is critical for exosomal HLA production in B cells. Together, these findings suggest a pivotal role of B cell activation in exosomal HLA production in vivo.
authors.affiliation: Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Arita
authors.forename: Eishi
authors.initials: E
authors.lastname: Baba
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Shibata
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Niiro
authors.forename: Shinji
authors.initials: S
authors.lastname: Shimoda
authors.forename: Taichi
authors.initials: T
authors.lastname: Isobe
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kusaba
authors.forename: Shuji
authors.initials: S
authors.lastname: Nakano
authors.forename: Mine
authors.initials: M
authors.lastname: Harada
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D001402:B-Lymphocytes / Q000187:drug effects / Q000502:physiology*; D015496:CD4-Positive T-Lymphocytes / Q000502:physiology; D023201:CD40 Ligand / Q000037:antagonists & inhibitors / Q000276:immunology / Q000494:pharmacology; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000737:chemistry; D022162:Cytoplasmic Vesicles / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D006680:HLA Antigens / Q000097:blood / Q000276:immunology / Q000378:metabolism*; D006684:HLA-DR Antigens / Q000097:blood / Q000276:immunology / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000097:blood / Q000276:immunology / Q000378:metabolism; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008213:Lymphocyte Activation / Q000502:physiology*; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000502:physiology; D011947:Receptors, Antigen, B-Cell / Q000819:agonists / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D051217:Toll-Like Receptor 9 / Q000819:agonists / Q000502:physiology; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D000911:Antibodies, Monoclonal; D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors; D006680:HLA Antigens; D006684:HLA-DR Antigens; D015395:Histocompatibility Antigens Class I; C508598:IL4 protein, human; D007476:Ionophores; D016328:NF-kappa B; D011947:Receptors, Antigen, B-Cell; C495371:TLR9 protein, human; D051217:Toll-Like Receptor 9; D023201:CD40 Ligand; D015847:Interleukin-4; D000077191:Wortmannin