innate immune recognition is mediated by a system of germline-encoded recep
tors that recognize conserved molecular patterns that are associated with m
icrobial pathogens. These receptors are coupled to signal transduction path
ways that control expression of a variety of inducible immune-response gene
s. Toll receptors and the associated signaling pathways of nuclear factor k
appa B may represent the most ancient host defense system found in mammals,
insects and plants.