Cutting Edge: Differential Sequestration of Plasma Membrane-Associated B Cell Antigen Receptor in Mature and Immature B Cells into Glycosphingolipid-Enriched Domains

Glycosphingolipid-enriched domains (GEDs) are believed to act as platforms for transduction of B cell Ag receptor (BCR)-induced signals from the cell surface. We sought to study whether differential sequestration of BCR into GEDs may contribute to the described intrinsic signaling differences between mature and immature B cells. In this study we found that mature B cells copolarize the BCR with GEDs following BCR aggregation, whereas transitional immature B cells do not. Although anti-BCR treatment leads to receptor aggregation by immature stage B cells, the aggregated complexes do not colocalize with GEDs. We found this difference to be independent of the isotype of the receptor, thereby associating this difference in BCR-GED colocalization to the developmental stage of the B cell. These findings suggest a structural basis for the developmentally regulated differences observed in Ag receptor-mediated signal transduction.