The respiratory tract is one of the main apparatus which is in daily contact with a wide variety of microorganisms, however, only on a few occasions is infection establish because of its innate immune response. Respiratory tract epithelial cells play a very important role in avoiding infectious agent colonization of the lungs, since this kind of cell can recognize microbial molecules through very specialized receptors such as Toll-like. Moreover these cells posses a broad variety of molecules which are related to local immunity. Respiratory tract epithelial cells are capable of producing several chemokines, antimicrobial peptides and other pro-inflammatory molecules.
