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Oxidative burst response to monosodium urate crystals in patients with Behçet’s syndrome

F. Gogus¹, I. Fresko², Y. Elbir³, E. Eksioglu-Demiralp³, H. Direskeneli⁴

¹Department of Physical Medicine and Rehabilitation, Division of Rheumatology, Gazi Medical Faculty, Ankara; ²Department of Internal Medicine, Division of Rheumatology, Cerrahpasa Medical Faculty, Istanbul; ³Division of Haematology-Immunology and ⁴Division of Rheumatology, Department of Internal Medicine, Marmara Medical Faculty, Istanbul, Turkey.

ABSTRACT
Objective
An erythematous response to intradermal injection of monosodium urate crystals (MSU) has been demonstrated in Behçet’s syndrome (BS). To further elucidate the pathogenesis of this response, the effects of MSU on in vitro oxidative burst reaction of neutrophils and monocytes were investigated.

Methods
Peripheral blood mononuclear cells from patients with Behçet’s syndrome (BS), rheumatoid arthritis (RA), familial Mediterranean fever (FMF) and healthy controls (HC) were incubated with 100 ng/ml phorbol myristate acetate (PMA) and MSU at different dosages (25-500 mg/ml). Oxidative burst reaction was evaluated in neutrophils and monocytes by flow cytometry.

Results
In patients with BS, oxidative burst of neutrophils was significantly increased compared to HC at 125 mg/ ml and 250 mg/ml dosages of MSU (p &Mac178; 0.001 and 0.004 respectively). In patients with FMF, there was also an increased oxidative burst reaction at 75 mg/ml, 250 g/ml and 500 mg/ml (p &Mac178; 0.007; 0.001 and 0.004 respectively). In patients with BS, oxidative burst of monocytes was increased only at 125 g/ml dosage of MSU (p &Mac178; 0.002). However, in patients with FMF monocyte burst response was increased at 25 mg/ ml, 75 mg/ml and 125 g/ml (p &Mac178; 0.004; < 0.0001; < 0.0001 and 0.002 respectively). In RA group, stimulation with PMA resulted in a higher oxidative burst reaction than FMF and BS (p &Mac178; 0.000 and p &Mac178; 0.008). No correlation was observed between oxidative burst of neutrophils or monocytes and intra-dermal responses to MSU crystals.

Conclusion
Oxidative burst reaction with MSU is augmented in neutrophils and monocytes of BS. However, the response is not specific and is unassociated with skin dermal test which has a high specificity for BS.

Key words
Behçet’s syndrome, oxidative burst reaction, monosodium urate crystals, urate skin test.

F. Gogus, MD, Assistant Professor; I. Fresko, MD, Associate Professor; Y. Elbir, Student in Msc; E. Eksioglu-Demiralp, MD, Professor; H. Direskeneli, MD,
Please address correspondence to: Feride Gogus, MD, Atatürk Bulvari No: 243 B Blok D:21, Kavaklidere, Ankara, Turkey.
E-mail: mtalat@ttnet.net.tr