Functional activity of plasma fibronectin in patients with diabetes mellitus.

Decreased wound healing and increased infection are major problems in patients with diabetes mellitus. Fibronectin plays a fundamental role in wound healing and acts as an opsonin for the phagocytosis of foreign antigens. The aim of this study was to ascertain the functional activity of plasma fibronectin from patients with diabetes mellitus. Initially, a modified Boyden chamber technique was used to measure cell migration on fibronectin purified from patient's plasma and an enzyme-linked immunosorbent assay was used to measure the binding of gelatin. A sandwich assay was developed that enabled the capture of fibronectin directly from patient's plasma without prior purification. With the use of a 96-well format, the binding of two different monoclonal antibodies could be compared simultaneously with the binding of gelatin and cell adhesion. In this way, differences in the function of particular domains of fibronectin from diabetic patients and control subjects could be measured. Results showed no difference between fibronectin from diabetic patients and control subjects with respect to the monoclonal antibodies binding in 1) the cell adhesion domain and 2) the heparin-binding domain. Furthermore, no detectable differences were noted with respect to cell adhesion, cell migration, or gelatin binding. These results suggest that diabetic patients receiving insulin treatment show no modulation of plasma fibronectin function, despite raised levels of circulating glucose.