Vates all regional lymph node B cells, but not those of the spleen or lung, as early as 24?48h after influenza infection (30), resulting in rapid and extensive gene expression changes, including up-regulation of surface CD69 and CD86 (67). Thus, the first signal regional lymph node B cells encounter following influenza virus infection is neither antigen nor T cell help, but type I IFN. Intrinsic c