Behçet's disease heterogeneity: cytokine production and oxidative burst of phagocytes are altered in patients with severe manifestations.

ABSTRACT

OBJECTIVES: To test the hypothesis that classical phagocytic functions are constitutively stimulated in patients with Behçet's disease (BD). METHODS: Four study groups were analysed active BD (aBD; n=30), inactive BD (iBD; n=31); septic patients (SP; n=25); healthy controls (HC; n=30). Microbicide activity against Streptococcus pneumoniae, Streptococcus sanguinis and Candida albicans was determined by means of 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction and absorbance read by ELISA. Flow cytometry analysis evaluated phagocytosis (zymosan particles and microrganisms) and oxidative burst by dihidrorhodamine oxidation before and after stimulation with phorbol myristate acetate (PMA). The supernatant of PBMC cultures under TLR or microbial stimuli and of neutrophil cultures under PMA, LPS or microbial stimuli were used for determination of cytokine production by ELISA. RESULTS: We found no significant differences between the BD patient groups and control groups with regard to oxidative burst, phagocytic activity, microbicide activity or cytokine production. However, the cells from patients with severe BD (based on clinical manifestation) exhibit significantly higher oxidative burst activity, both before and after PMA stimulation, compared to cells from patients with mild BD. Furthermore, we found significant correlations between the BD patients' scores on the simplified Behçet's Disease Current Activity Form adapted for Portuguese (BR-BDCAFs) and Streptococcus sanguinis-stimulated production of IL23 by PBMC and IL8 by neutrophils, and between BR-BDCAFs score and constitutive production of TNF-α, IFNγ, IL6 and IL23 by PBMC. CONCLUSIONS: Patients with severe active BD do exhibit phagocytic dysfunction and some evidence of constitutive activation regarding oxidative burst and cytokine production.