Abstract

How do metazoans balance immune responses to commensal and pathogenic bacteria? In a paper just published in Cell Host & Microbe Lhocine et al. report the identification of a protein in the fruit fly Drosophila melanogaster that functions to dampen the immune response to commensals. Infection of D. melanogaster with Gram-negative bacteria activates the IMD (immune deficiency) signal transduction system, which results in the synthesis of antimicrobial peptides (AMPs).