Structural and functional aspects of the collectin SP-A

Surfactant protein A (SP-A), member of the collectin family, is implicated in innate host defense of the lung. SP-A is a "pattern recognition molecule" and interacts with glycoconjugates on the surface of micro-organisms. It protects the lung by interacting with a wide variety of potential pathogens, including viruses, bacteria and fungi. This may result in enhanced killing and clearance by phagocytes. SP-A is a link between the innate and adaptive immune system because it directly affects lymphocyte proliferation and function. Although most extensively studied in the lung, SP-A is found in a number of other sites in the body. The presence of SP-A at these mucosal surfaces, which are in close contact with numerous potentially harmful micro-organisms, supports a more general role for this collectin in mucosal defense.