Inhibition of polymorphonuclear leukocyte respiratory burst by elevated glucose concentrations in vitro

Abstract

Although impaired polymorphonuclear leukocyte (PMN) function may be a cause of infectious complications in diabetic patients, the mechanisms of altered cell function are not understood. Our studies of PMN function in healthy subjects demonstrated significant reduction in the respiratory burst after 30 min of in vitro cell exposure to glucose concentrations greater than 11 mM (200 mg/dl). The respiratory burst was reduced 28 +/- 5 and 74 +/- 7% in PMNs incubated with 11 and 56 mM glucose, respectively. The impairment was independent of the cell stimulus (chemotactic peptide, calcium ionophore, or phorbol ester) and was not affected by sorbinil or myo-inositol. Because both D- and L-glucose had similar inhibitory effects, a nonenzymatic mechanism appeared to be the cause of impaired PMN function. Although mannitol and sorbitol did not affect cell function, monosaccharides (glucose, mannose, fructose) that form Schiff-base adducts with protein inhibited PMN function. These findings suggest a potential role for protein glycosylation in glucose-induced impairment of PMN function.