Innate Immunity: PIMS knows friends and foes.

The article reports that bacterially derived peptidoglycan activates the immune defficiency (IMD) system which results in the synthesis of antimicrobial peptides (AMPs). It reveals that basal levels of PIMS transcription are dependent on the presence of commensal bacteria. It concludes that PIMS, together with other proteins including PGRP-LB and PGRP-SC1, ensures immune tolerance by providing a buffered threshold for activation of the immune response by peptidoglycan.