Antimicrobial peptides and proteins in the innate defense of the airway surface.

Recent studies have advanced our understanding of innate immune mechanisms that protect the airways and maintain a sterile lung. Multiple antimicrobial peptides and proteins have been identified in airway secretions and their roles are beginning to be established in animal models. Moreover, evidence for coupling between the innate and adaptive immune systems is beginning to emerge. The understanding of the innate airway defense system offers the opportunity for the development of novel therapeutic approaches.