Immunoassay of platelet-derived growth factor in the blood of patients with diabetes mellitus.

Platelet-derived growth factor (PDGF) is a powerful mitogen for many cell types, and is believed to play a major role in wound healing when released from platelets at sites of injury. In diabetes mellitus, it has been proposed that premature release of PDGF from platelets impairs the ability of platelets to initiate healing, and also accelerates the development of diabetic complications such as angiopathy by increasing plasma-borne PDGF. However, plasma samples from diabetic patients have not previously been assayed for PDGF using suitable techniques. A sensitive monoclonal enzyme-linked immunoassay for PDGF was applied to plasma and serum samples from 18 healthy control subjects and 60 diabetic patients. Neither plasma nor serum PDGF concentrations differed significantly between control subjects, insulin-dependent, and non-insulin-dependent diabetic patients. However, 23% of the diabetic subjects had serum PDGF levels above the control range. Limited joint mobility, which is characterised by joint contractures and collagen deposition in the skin, and is associated with microvascular disease, was used as a marker of diabetic complications. Limited joint mobility affected 43% of the diabetic subjects. Patients with moderate limited joint mobility had had diabetes significantly longer than those without limited joint mobility (means 17 years and 9 years, respectively, p = 0.008). However, limited joint mobility was not associated with elevated serum or plasma PDGF in insulin-dependent or non-insulin-dependent diabetes. We conclude that complications of diabetes are unlikely to be caused by changes in systemic levels of PDGF.(ABSTRACT TRUNCATED AT 250 WORDS)