Activation of second messenger pathways in alveolar macrophages by endotoxin

The alveolar macrophage plays an important role in immune surveillance of the lung. Early responses to infectious agents by macrophages can decrease tissue injury and promote recovery of the host. Macrophage responses to pathogens are the cornerstone of the innate or nonspecific immune system. In particular, the response of macrophages to endotoxin from Gram negative bacteria has been the focus of many recent studies. The recent discovery of the endotoxin receptor has accelerated the study of signalling in macrophages. This review focuses on the downstream events that occur following exposure of the alveolar macrophage to endotoxin.