Pulmonary collectins and innate host defense of the lung

Surfactant proteins A and D (SP-A and SP-D) are members of the collectin fa mily of Polypeptides expressed in the respiratory tract that bind bacterial , fungal and viral pathogens, enhancing their opsonization and killing by p hagocytic cells. Clearance of bacterial pathogens including group B strepto cocci, Haemophilus influenza, Pseudomonas aeruginosa and viral pathogens, r espiratory syncytial virus, adenovirus and influenza A virus, was deficient in SP-A(-/-) mice. SP-A deficiency was associated with enhanced inflammati on and synthesis of proinflammatory cytokines. SP-D-/- mice cleared these b acteria as efficiently as wild-type mice; however, clearance of viral patho gens was deficient in SP-D-/- mice and associated with increased inflammati on. SP-A and SP-D play critical and distinct roles in the regulation of alv eolar macrophage function and inflammation, contributing to innate defense of the lung. (C) 2001 Editions scientifiques et medicales Elsevier SAS.