While frequent infection is an important cause of mortality in patients with diabetes mellitus, the precise mechanism has not been explored. On the other hand, stimulated neutrophils producea burst of oxidative metabolism which results in the death of bacteria. Chemiluminescence, whichis reported to be a sensitive indicator of oxidative metabolism, is simultaneously correlated withantimicrobial activity. We examined luminol-dependentchemiluminescence (LDCL) using whole bloodin streptozotocin (STZ)-induced diabetic rats. Four days after ip administration of STZ (60 mg/kg), the LDCL activity in the diabetic rats decreased significantly Comparid control rats (4 days: Cont, 5.12±1.53, DM, 1.10±0.07, p<0.01; 17 days: DM, 1.01±0.39, p<0.05 (KC/min2/106 gran.)). But the blood glucose levels were significantly more eleveated in the diabetic rats than in controlrats (4 days: 399±9mg//dl, 17 days: 598±8mg/dl, Cont.: 77±8mg/dl). Ten days after administrationof NPH insulin to diabetic rats, the LDCL activity significantly increased (O.04U: 1.61±0.09; 0.40U: 1.99±0.47; 4.00 U: 3.3±0.43 KC/min2/106 gran.). These results indicate that an increased susceptibility to infection in diabetic rats results fromimpaied of neutrophils to produce ability active oxygen species.
Insulin autoantibodies (IAAs) are regarded as a serological marker of on-going autoimmunity and developement of insulin dependent diabetes mellitus (IDDM) in Caucasians. Since there have been no reports on IAAs in Japan, we studied IAAs in relatives of Japanese patients with IDDM and correlated the results with HLA, islet cell surface antibodies (ICSA) and beta cell function. Twenty non-diabetic relatives of patients with IDDM were studied. IAAs were measured by the polyethyleneglycol (PEG) precipitation method with 125I-human insulin and expressed as insulin binding capacity. HLA was detected by a microcytotoxicity test and ICSA were examined by the indirect immunofluorescence method using Ballb/c mouse islet cells. Beta cell function was studied by a 75g oral glucose tolerance test (0-GTT). Four of 20 sera from relatives showed high 125I-human insulin binding, well above the mean+3 SD of those from helthy controls. No sera from healthy controls showed such high 125I-insulin binding. IAA-positive sera were obtained from 2 siblings and 2 children. There was no relation between IAAs and HLA, ICSA and beta cell function tested by 75g O-GTT. These results suggest that IAAs may be a serological marker of Japanese individuals at high risk to develop IDDM.