Innate recognition of bacterial products constitutes a principal bulwark of our defenses against infection. In vertebrates, innate mechanisms both instruct the adaptive immune response and provide immediate protection from infectious challenge. In all lower phyla, innate mechanisms represent the totality of immune protection, attesting to both the power and evolutionary precedence of these mechanisms.
Although the workings of the adaptive immune system may be traced in a satisfying way from generation of diversity to ligation of surface immunoglobulin to clonal expansion, a similarly complete and satisfying view of innate recognition is not in hand. Even the best characterized example of innate recognition, the inflammatory response to bacterial LPS (endotoxin), has a yawning gap in the steps of its progression. Results of long anticipated work published in a recent issue of Science (1) and in this issue of The Journal of Experimental Medicine (2) have now...
