Single-cell gene expression of lymph node B cell-interacting reticular cells

Efficient germinal center formation requires the coordinated movement of B cells between distinct regions of the B cell follicle where their fate and function is governed by the integration of cues from their interacting partners. While CXCL13 is known to be important for B cell chemoattraction and follicle formation, the molecular identity of B cell-interacting reticular cells remains ill-defined. Moreover, how CXCL13-expressing, B-cell interacting reticular cells are reprogramed to cater to the developing germinal center remains unclear. Here we use the Cxcl13-Cre/TdTomato mouse model to genetically target and decipher the cellular composition of lymph node CXCL13-expressing reticular cells under steady-state and inflammatory conditions. Moreover, we examine the consequence of cell-specific, genetic perturbation of CXCL12 on the molecular identity of the reticular cell network. Transcriptomic analyses revealed that B cell follicle reticular cell subset specification is predetermined in the steady-state, although additional transcriptional changes accompany germinal center formation. Although genetic perturbation of CXCL12 alters GC topology, the molecular identity of the underlying reticular cells remains largely unperturbed.