The oxidative metabolism of circulating phagocytes in ankylosing spondylitis: determination by whole blood chemiluminescence.

OBJECTIVE Superoxide anion radicals within the human body are regarded as a major cause of inflammation. However, their role in the pathogenesis of ankylosing spondylitis (AS) has not been well identified. This study aimed at investigating the relation between AS and the oxidative metabolism of phagocytes in whole blood. METHODS 24 patients with classic AS were examined to determine their clinical status; complete blood count, erythrocyte sedimentation rate (ESR), and C reactive protein (CRP) were determined, and levels of the superoxide anion radicals in the patients with AS and 21 healthy subjects were assessed by the ultraweak chemiluminescence method. Subsequently, the relation between this disease and phagocytes was examined by using N-formyl-methionyl-leucyl-phenylalanine (fMLP) and phorbol-12-myristate-13-acetate (PMA) stimulants. RESULTS In clinical assessments, patients with AS had abnormally raised serum CRP (>10 mg/l) and ESR (>15 mm/1st h) levels. In contrast with healthy subjects, patients with AS had significantly increased rates of superoxide anion radical production in their whole blood either in the resting state or with either fMLP or PMA stimulation. In addition, chemiluminescence maximum light intensity was significantly higher in patients with AS than in healthy subjects after fMLP or PMA stimulation. CONCLUSIONS Our results suggest that the phagocytes of patients with AS are partly activated in the resting state, and are sensitive to fMLP or PMA stimulation. The priming of phagocytes in the bloodstream is likely to be a causative factor in the onset of AS.