The adaptive immune system relies on rare cognate lymphocytes to detect pathogen-derived antigens. Naïve lymphocytes recirculate through secondary lymphoid organs in search of cognate antigen. Here, we show that the naïve-lymphocyte recirculation pattern is controlled at the level of innate immune recognition, independent of antigen-specific stimulation. We demonstrate that inflammation-induced lymphocyte recruitment to the lymph node is mediated by the remodeling of the primary feed arteriole, and that its physiological role is to increase the efficiency of screening for rare antigen-specific lymphocytes. Our data reveal a mechanism of innate control of adaptive immunity: by increasing the pool of naïve lymphocytes for detection of foreign antigens via regulation of vascular input to the local lymph node.