Llibre, AlbaLópez-Macías, ConstantinoMarafioti, TeresaMehta, HemaPartridge, AmyKanzig, CarinaRivellese, FeliceGalson, Jacob D.Walker, Lucy J.Milne, PaulPhillips, Rodney E.Kelly, Dominic F.Freeman, GordonEl Shikh, Mohey EldinKlenerman, PaulWillberg, Christian B.2016-03-012016Llibre, A., C. López-Macías, T. Marafioti, H. Mehta, A. Partridge, C. Kanzig, F. Rivellese, et al. 2016. “LLT1 and CD161 Expression in Human Germinal Centers Promotes B Cell Activation and CXCR4 Downregulation.” The Journal of Immunology Author Choice 196 (5): 2085-2094. doi:10.4049/jimmunol.1502462. http://dx.doi.org/10.4049/jimmunol.1502462.0022-1767http://nrs.harvard.edu/urn-3:HUL.InstRepos:25658379Germinal centers (GCs) are microanatomical structures critical for the development of high-affinity Abs and B cell memory. They are organized into two zones, light and dark, with coordinated roles, controlled by local signaling. The innate lectin-like transcript 1 (LLT1) is known to be expressed on B cells, but its functional role in the GC reaction has not been explored. In this study, we report high expression of LLT1 on GC-associated B cells, early plasmablasts, and GC-derived lymphomas. LLT1 expression was readily induced via BCR, CD40, and CpG stimulation on B cells. Unexpectedly, we found high expression of the LLT1 ligand, CD161, on follicular dendritic cells. Triggering of LLT1 supported B cell activation, CD83 upregulation, and CXCR4 downregulation. Overall, these data suggest that LLT1–CD161 interactions play a novel and important role in B cell maturation within the GC in humans.en-USJournal Article2016-03-0110.4049/jimmunol.1502462