Lung defences: an overview

Lung defences are dependant on a complex array of mechanisms in the upper airways, which must to be differentiated from those of the distal airways. However, the first lines of defence in the proximal and distal airways are predominantly based on mechanical barriers and several mechanisms related to innate immunity. If pathogens or antigens reach the interstitium, dendritic cells will take up these intruders, reporting antigenic information to the pulmonary lymph nodes, where an adaptive immunity will be generated. Dendritic cells, by doing so, bridge innate immunity with adaptive immunity. Knowledge of these mechanisms is key when modulating immunity to increase defence mechanisms or decrease allergic phenomena.