B cell activation regulates exosomal HLA production

Eur J Immunol. 2008 May;38(5):1423-34. doi: 10.1002/eji.200737694.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Androstadienes / pharmacology
  • Antibodies, Monoclonal / immunology
  • Antibodies, Monoclonal / pharmacology
  • B-Lymphocytes / drug effects
  • B-Lymphocytes / physiology*
  • CD4-Positive T-Lymphocytes / physiology
  • CD40 Ligand / antagonists & inhibitors
  • CD40 Ligand / immunology
  • CD40 Ligand / pharmacology
  • Cell Line, Transformed
  • Cell Line, Tumor
  • Coculture Techniques
  • Culture Media, Conditioned / chemistry
  • Cytoplasmic Vesicles / metabolism*
  • Enzyme Inhibitors / pharmacology
  • Enzyme-Linked Immunosorbent Assay / methods
  • Exocytosis / drug effects
  • Exocytosis / physiology*
  • HLA Antigens / blood
  • HLA Antigens / immunology
  • HLA Antigens / metabolism*
  • HLA-DR Antigens / blood
  • HLA-DR Antigens / immunology
  • HLA-DR Antigens / metabolism
  • Histocompatibility Antigens Class I / blood
  • Histocompatibility Antigens Class I / immunology
  • Histocompatibility Antigens Class I / metabolism
  • Humans
  • Interleukin-4 / pharmacology
  • Ionophores / pharmacology
  • Leukocytes, Mononuclear / metabolism
  • Lymphocyte Activation / physiology*
  • NF-kappa B / antagonists & inhibitors
  • NF-kappa B / physiology
  • Receptors, Antigen, B-Cell / agonists
  • Receptors, Antigen, B-Cell / physiology
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • Toll-Like Receptor 9 / agonists
  • Toll-Like Receptor 9 / physiology
  • Wortmannin

Substances

  • Androstadienes
  • Antibodies, Monoclonal
  • Culture Media, Conditioned
  • Enzyme Inhibitors
  • HLA Antigens
  • HLA-DR Antigens
  • Histocompatibility Antigens Class I
  • IL4 protein, human
  • Ionophores
  • NF-kappa B
  • Receptors, Antigen, B-Cell
  • TLR9 protein, human
  • Toll-Like Receptor 9
  • CD40 Ligand
  • Interleukin-4
  • Wortmannin