Some characteristics of neutrophils from diabetic patients and their relation to the levels of circulating immune complexes.

In the present work we studied different characteristics of neutrophils from diabetic patients and their relation to the levels of circulating immune complexes (CIC). Twenty-five insulin-dependent (IDD) and 25 non-insulin-dependent diabetic (NIDD) patients were evaluated. Each group was then subdivided according to the presence or absence of microvascular complications (MC). We found that the chemiluminescence (CL) emitted by opsonized zymosan (Zop) stimulated neutrophils in IDD and NIDD patients was significantly increased when compared to healthy subjects (p less than 0.01 and p less than 0.02, respectively). The CL values were correlated to CIC levels and both parameters were related to the presence of MC. On the other hand, the percentage of neutrophils capable of reducing nitroblue tetrazolium was diminished in the two groups of diabetic patients (p less than 0.05 for IDD and p less than 0.01 for NIDD). The percentage of neutrophils with functional C3b receptors was normal in diabetic patients; however, the proportion of phagocytic cells through Fc receptors was significantly decreased in both types of patients (p less than 0.05 and p less than 0.01 for IDD and NIDD, respectively). Furthermore, the number of granulocytes with immune complexes (IC) bound to their cell surface was increased in diabetics. We suggest that the increase of CIC level may produce an increase in IC binding to the neutrophil membrane. These IC could block the Fc receptors, diminish phagocytic capacity and, simultaneously, stimulate the release of toxic oxygen products, thus contributing to produce tissue damage.