BLC expression in pancreatic islets causes B cell recruitment and lymphotoxin-dependent lymphoid neogenesis

CXCR5, the receptor for B lymphocyte chemoattractant (BLC), is required for normal development of Peyer's patches, inguinal lymph nodes, and splenic f ollicles. To test the in vivo activity of BLC in isolation of other lymphoi d organizers, transgenic mice were generated expressing BLC in the pancreat ic islets. In addition to attracting B cells, BLC expression led to develop ment of lymph node-like structures that contained B and T cell zones, high endothelial venules, stromal cells, and the chemokine SLC. Development of t hese features was strongly dependent on B lymphocytes and on lymphotoxin al pha 1 beta 2 and could be reversed by blocking lymphotoxin alpha 1 beta 2. These findings establish that BLC is sufficient to activate a pathway of ev ents leading to formation of organized lymphoid tissue.