Superoxide release in juvenile systemic lupus erythematosus

The objective of this study was to analyze the un-stimulated and stimulated release of superoxide anion (O₂ ⁻) by granulocytes and monocytes in juvenile systemic lupus erythematosus (jSLE). The un-stimulated and phorbol myristate acetate (PMA, 30 nM)-induced O₂ ⁻by granulocytes and monocytes were determined in six different times of incubation in patients with 23 jSLE and 28 controls. The analysis compared the jSLE group, which was classified into two subgroups by SLEDAI in one inactive subgroup (score <3) (n = 13 patients) and one active subgroup (score ≥3) (n = 10 patients) to the same control group. At time of blood withdrawal, 13 (56.52%) had inactive and 10 (43.47%) patients had active SLE. jSLE patients’ granulocytes and monocytes had always a lower un-stimulated O₂ ⁻ production when compared to controls. Stimulated granulocytes had an increased O₂ ⁻ production at baseline followed by a significant lower production at 60 min in jSLE when compared to controls. Stimulated monocytes had a similar O₂ ⁻ production among patients with jSLE and controls. The results suggest a defect in phagocytic function in jSLE. The significant higher release of O₂ ⁻ in the assays of the stimulated granulocytes, in the initial instances, the so-called respiratory burst, could be attributed to the inflammatory state of phagocytes.