Host resistance to infection: genetic control of lipopolysaccharide responsiveness by Toll-like receptor genes

Gram-negative bacterial lipopolysaccharide evokes a protective inflammatory response in the normal host. Through genetic analysis of mutant mice, the gene encoding Toll-like receptor 4 (Tlr4) was recently identified as a critical component of this host defense mechanism. Tlr4is a member of an ancient gene family that regulates antimicrobial host defense in plants, invertebrates and mammals.