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 c ell types, and is believed to play a major role in wound healing when released from platelets at sites of injury. In diabetes mellitus, it h as been proposed that premature release of PDGF from platelets impairs the ability of platelets to initiate healing, and also accelerates th e development of diabetic complications such as angiopathy by increasi ng plasma-borne PDGF However, plasma samples from diabetic patients ha ve not previously been assayed for PDGF using suitable techniques. A s ensitive monoclonal enzyme-linked immunoassay for PDGF was applied to plasma and serum samples from 18 healthy control subjects and 60 diabe tic patients. Neither plasma nor serum PDGF concentrations differed si gnificantly between control subjects, insulin-dependent, and non-insul in-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 a s a marker of diabetic complications. Limited joint mobility affected 43 % of the diabetic subjects. Patients with moderate limited joint mo bility had had diabetes significantly longer than those without limite d joint mobility (means 17 years and 9 years, respectively, p = 0.008) . However, limited joint mobility was not associated with elevated ser um or plasma PDGF in insulin-dependent or non-insulin-dependent diabet es. We conclude that complications of diabetes are unlikely to be caus ed by changes in systemic levels of PDGF The delayed healing associate d with diabetes is not due to a deficit in PDGF available from platele ts.