title: Extrafollicular activation of lymph node B cells by antigen-bearing dendritic cells.
abstract: In contrast to naïve T cells that recognize short antigen-derived peptides displayed by specialized antigen-presenting cells, immunoglobulin receptors of B lymphocytes primarily recognize intact proteins. How and where within a lymph node such unprocessed antigens become available for naïve B cell recognition is not clear. We used two-photon intravital imaging to show that, after exiting high-endothelial venules and before entry into lymph node follicles, B cells survey locally concentrated dendritic cells. Engagement of the B cell receptor by the dendritic cell (DC)-associated antigen leads to lymphocyte calcium signaling, migration arrest, antigen acquisition, and extrafollicular accumulation. These findings suggest a possible role for antigen-specific B-DC interactions in promoting T cell-dependent antibody responses in vivo.
authors.affiliation: Lymphocyte Biology Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD 20892, USA.
authors.forename: Hai
authors.initials: H
authors.lastname: Qi
authors.forename: Jackson G
authors.initials: JG
authors.lastname: Egen
authors.forename: Alex Y C
authors.initials: AY
authors.lastname: Huang
authors.forename: Ronald N
authors.initials: RN
authors.lastname: Germain
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology*; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D002465:Cell Movement; D048430:Cell Shape; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000276:immunology*; D004705:Endocytosis; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009113:Muramidase / Q000276:immunology; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000941:Antigens; D011947:Receptors, Antigen, B-Cell; C421864:hen egg lysozyme; D009113:Muramidase; D002118:Calcium