Alveolar macrophages - key coordinators of host defense.- Lung dendritic cells and pulmonary defense mechanisms against bacteria.- CD4 T cell immunity in the lung.- Neutrophil mediated defenses in bacterial pneumonia.- Toll-like receptors in the epithelium.- Type I IFN signaling in bacterial pneumonia.- Transcriptional signaling hubs in epithelial cells during pneumonia.- Innate immune responses in Ventilator Associated Pneumonia.- Streptococcus pneumoniae: The prototype of lung responses in pneumonia.- Staphylococcus aureus infection of the respiratory tract.- Pseudomonas aeruginosa: the consummate opportunistic pathogen of the lung.