Activation of B cells by antigens on follicular dendritic cells.
A need for antigen-processing and presentation to B cells is not widely appreciated. However, cross-linking of multiple B cell receptors (BCRs) by T-independent antigens delivers a potent signal that induces antibody responses. Such BCR cross-linking also occurs in germinal centers where follicular dendritic cells (FDCs) present multimerized antigens as periodically arranged antigen-antibody complexes (ICs). Unlike T cells that recognize antigens as peptide-MHC complexes, optimal B cell-responses are induced by multimerized FDC-ICs that simultaneously engage multiple BCRs. FDC-FcgammaRIIB mediates IC-periodicity and FDC-BAFF, FDC-IL-6 and FDC-C4bBP are co-stimulators. Remarkably, specific antibody responses can be induced by FDC-ICs in the absence of T cells, opening up the exciting possibility that people with T cell insufficiencies may be immunized with T-dependent vaccines via FDC-ICs.
El Shikh
Mohey Eldin M
ME
Department of Microbiology and Immunology, Virginia Commonwealth University, PO Box 980678, Richmond, VA 23298-0678, USA.
El Sayed
Rania M
RM
Sukumar
Selvakumar
S
Szakal
Andras K
AK
Tew
John G
JG
D000818:Animals; D017951:Antigen Presentation; D000936:Antigen-Antibody Complex / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D020566:Dendritic Cells, Follicular / Q000276:immunology*; D006801:Humans; D008213:Lymphocyte Activation; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
D000936:Antigen-Antibody Complex; D011947:Receptors, Antigen, B-Cell