Fig. 2

Simplified schematic presentation of the human respiratory immune system. The upper respiratory epithelium, lining the inner surface of the trachea, bronchi and bronchioles, is composed of a pseudostratified layer of ciliated cells, mucus-producing cells and basal cells, and is responsible for rapid clearance of inhaled particulate antigen with the mucociliary escalator. The distal regions of the lung epithelium, the alveolar septa, represent the site of the gas exchange. In both regions, macrophages are located at the apical side of the epithelial layer and protect it from the inhaled antigen cells by phagocytosis. Dendritic cells will capture antigens, process and present antigen peptide to naive T cells, and trigger their differentiation into antigen-specific effector T cells. Figure as shown in and reprinted with permission from Nanomedicine (Futuremedicine)