Objective: Despite unknown etiology, immunologic alterations and neutrophil hyperfunctions may be involved in the etiopathogenesis of Behcet's Disease (BD). The purpose of the study was to investigate whether adenosine deaminase (ADA) activity, accepted as a nonspecific marker of T lymphocyte activation, may have a potential role in ED. and also may be related to the production of reactive oxygen species (ROS) by neutrophils. 

Design and methods: ADA activities and malondialdehyde (MDA; endproduct of lipid peroxidation induced by ROS) levels in both plasma and erythrocytes were spectrophotometrically measured in 25 patients with BD and also in 25 healthy controls. 

Results: ADA activity was found to be higher in plasma, but lower in erythrocytes; plasma and erythrocyte MDA levels were higher in ED patients than those of controls. In addition, plasma ADA activity was positively related to MDA levels in both plasma (p < 0.05) and erythrocytes (p < 0.01). There was also positive correlation between MDA levels (p < 0.05), but negative correlations between ADA activities (p < 0.01) and also between ADA and MDA values in erythrocytes (p < 0.01) of ED patients. 

Conclusion: These findings may provide some evidence for a potential role of T lymphocyte activation in ED as reflected by increased plasma ADA activity, and for the presence of possible interrelationship between activated T cells and neutrophil hyperfunctions. such as ROS generation, as reflected by increased MDA levels.