Cutting edge: JAM-C controls homeostatic chemokine secretion in lymph node fibroblastic reticular cells expressing thrombomodulin.

The development and maintenance of secondary lymphoid organs, such as lymph nodes, occur in a highly coordinated manner involving lymphoid chemokine production by stromal cells. Although developmental pathways inducing lymphoid chemokine production during organogenesis are known, signals maintaining cytokine production in adults are still elusive. In this study, we show that thrombomodulin and platelet-derived growth factor receptor α identify a population of fibroblastic reticular cells in which chemokine secretion is controlled by JAM-C. We demonstrate that Jam-C-deficient mice and mice treated with Ab against JAM-C present significant decreases in stromal cell-derived factor 1α (CXCL12), CCL21, and CCL19 intranodal content. This effect is correlated with reduced naive T cell egress from lymph nodes of anti-JAM-C-treated mice.