The immune cells, but also platelets, epithelial, and endothelial cells, and other cells localized at a site of injury, activate and generate a wide spectrum of biologically active substances, such as pro-inflammatory cytokines and chemokines (TNFα, interleukins (IL)-1β, -6, and -8, proteases, reactive oxygen species (ROS), etc. The substances produced by the activated cells or released from the destroyed cells stimulate a chemotaxis of additional immune cells into the lung, which aggravate the injury, but might be also used as biomarkers of the acute phase of ALI/ARDS [16,17]. This evidence concerns the gene TNF and acute respiratory distress syndrome.