Abstract
The collectins are soluble lectins containing collagen-like regions which are found in plasma and in the lung surfactant. They have been characterised in mammals and birds and the group includes three plasma proteins (mannanbinding protein, bovine conglutinin and bovine collectin-43) and two lung surfactant proteins (SP-A and SP-D). They have an overall similarity in subunit, and three-dimensional structure, to each other, and also to the complement component C1q, in that they all contain globular ‘heads’ linked to triplehelical, collagen-like ‘stalks’. The globular ‘heads’ of the collectins are able to recognize carbohydrate structures on pathogens and thus trigger effector functions, or cell-binding, via the collagen-like ‘stalks’. Thus the collectins by virtue of their antibody-independent, carbohydrate recognition properties may play an important role in innate immunity especially in the very young or in those with an inability to produce antibodies.
