[Plasma fibronectin in the aged]

Biochemical and functional characteristics of the plasma fibronectin in very old human individuals (within the range 86a-95a) were investigated. While the molecular weight was unchanged as compared to control fibronectin, binding experiments showed a clear-cut reduction in the affinity to gelatin. The opsonizing activity for connective tissue fragments liberated by thermal injury or operation trauma is therefore reduced in old age and such particles are removed from the circulation at a slower pace. In contrast to the elevated plasma fibronectin concentration this group of very old people showed no general irregularities as far as acute phase proteins are concerned. In addition, the hemolytical activity of C1 and C3 complement components, which both form complexes with fibronectin, was unchanged.