Circulating monocytes are activated in newly diagnosed type 1 diabetes mellitus patients

Abstract

SUMMARY: Investigations in the BB rat and the non-obese diabetic (NOD) mouse have provided substantial evidence for the involvement of the monocyte/macrophage system in the development of type 1 diabetes mellitus. However, it is not known whether monocytes play the same role in the pathogenesis of human type 1 diabetes. We investigated this problem in a longitudinal study of 29 recent-onset type 1 diabetes mellitus patients. Monocyte chemotaxis, phagocytosis and superoxide production as well as metabolic and haematological parameters were studied immediately after diagnosis and 6 months later. At diagnosis the patients had activated casein and C5a chemotaxis (casein 70 ± 9 versus 150 ± 5 (mean ± s.e.m.), P < 0001; C5a 137 ± 10 versus 158 ±5, P < 005 (activation immobilizes monocytes, reducing the measured values)), and activated superoxide production (3·6 ± 03 versus 3·0 ± 03, P < 0·05), After 6 months casein chemotaxis (115 ±16 versus 150 ±5, P < 005) and Candida phagocytosis (33 ±01 versus 2·8 ±0·2. P < 0.001) were still activated. There was no correlation with other clinical or paraclinical parameters. We conclude that the circulating monocytes in newly diagnosed type 1 diabetes patients are activated. It is reasonable to expect that monocytes at the local site of inflammation in pancreas are even further activated. This could play a pathogenic role in β cell destruction.