Polyvalent antigens stabilize B cell antigen receptor surface signaling microdomains.
The B cell Ag receptor (BCR) can distinguish subtle differences in Ag structure and trigger differential responses. In this study, we analyzed the effects of Ag valency on the signaling and Ag-targeting functions of the BCR. Although both paucivalent and polyvalent Ags induced the redistribution of the surface BCR into polarized caps, polyvalent Ag-induced BCR caps persisted. Ganglioside G(M1), a lipid raft marker, and tyrosine-phosphorylated proteins, but not CD45 and transferrin receptor, were concentrated in BCR caps, suggesting BCR caps as surface-signaling microdomains. Prolonged BCR caps were concomitant with an increase in the level and duration of protein tyrosine phosphorylation and a reduction in BCR internalization and movement to late endosomes/lysosomes. Thus, Ag valency influences B cell responses by modulating the stability of BCR-signaling microdomains and BCR trafficking.
Thyagarajan
Rathna
R
Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA.
Arunkumar
Nandini
N
Song
Wenxia
W
D000818:Animals; D000941:Antigens / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D001665:Binding Sites / Q000276:immunology; D003432:Cross-Linking Reagents / Q000378:metabolism; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism; D007424:Intracellular Fluid / Q000276:immunology / Q000378:metabolism; D007700:Kinetics; D021962:Membrane Microdomains / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D021381:Protein Transport / Q000276:immunology; D011940:Receptor Aggregation / Q000276:immunology; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction / Q000276:immunology*; D014407:Tumor Cells, Cultured
D000941:Antigens; D003432:Cross-Linking Reagents; D007140:Immunoglobulin Fab Fragments; D011947:Receptors, Antigen, B-Cell; D019000:Phosphotyrosine