Antigen-affinity controls pre-germinal centser B cell selection by promoting Mcl-1 induction through BAFF receptor signaling
Upon antigen encounter, the responsive B cell pool undergoes stringent selection which eliminates cells with low B cell receptor (BCR) affinity. Already before formation of the germinal center, activated B cells of low-affinity are negatively selected in a process that is molecularly not well understood. In this study, we investigated the mechanism behind pre-GC affinity-mediated B cell selection. We applied affinity mutants of HEL antigen and found that rapidly after activation B cells become highly dependent on the cytokine BAFF. Moreover, expression of BAFF receptor CD268 is regulated in a BCR-affinity dependent fashion. High affinity responses via BAFF correlated with PI3K activation, which controlled expression of the pro-survival protein Mcl-1, and thereby increased survival. In the presence of excess BAFF, or in absence of the Mcl-1 antagonist Noxa, more low-affinity B cells survived the first two days after antigen encounter. This resulted in increased numbers of antigen-specific B cells of low affinity upon immunization and reduced the overall affinity of cells that contributed to the germinal center reaction. Our findings elucidate a crucial molecular pathway of B cell selection in the earliest phases of activation by identifying a novel link between BCR affinity and BAFF-R signaling towards Mcl-1.
|ISBN||2045-2322 (Electronic) 2045-2322 (Linking)|
|Authors||Wensveen, F. M.; Slinger, E.; van Attekum, M. H.; Brink, R.; Eldering, E.;|
|Publisher Name||Scientific Reports|
|URL link to publisher's version||http://www.ncbi.nlm.nih.gov/pubmed/27762293|
|OpenAccess link to author's accepted manuscript version||https://publications.gimr.garvan.org.au/open-access/13943|