Defective phagocytosis in insulin controlled diabetics: evidence for a reaction between glucose and opsonising proteins.

Neutrophils from diabetic patients controlled with insulin showed impaired phagocytosis of a yeast, Candida guilliermondii. The defect was detected by measuring the initial rate of phagocytosis at optimal concentrations of phagocytes and organisms in autologous plasma. By mixing normal neutrophils in diabetic plasma and vice versa both cellular and plasma abnormalities were shown. The defect was reproduced by incubating normal plasma at a D-glucose concentration of 15 mmol/l for 3 h or for shorter periods at higher concentrations of glucose. The data suggest that defective phagocytosis is partly due to a reaction between glucose and the plasma proteins concerned with opsonisation. Defective phagocytosis may be important not only in coping with infections but also in other diabetic complications as plasma proteins are concerned with the removal of damaged or effete cells as well as foreign antigens.