Deficient saliva-induced NETosis in response to saliva from patients with Behçet disease due to composition of protein-free fraction of saliva. Neutrophils were stimulated to NETosis and examined by immunofluorescence microscopy and NET formation quantified as described in “Materials and methods.” Representative images are shown in supplementary Figure 6. (A) Neutrophils were stimulated with saliva from 5 patients with Behçet disease, 5 patients with SLE or with saliva from normal donors. (B) Western blot of sialyl Lewis^X in saliva from normal healthy donor (ND) and patient with Behçet’s disease (BD). The same pattern was found in all samples of patients with Behçet disease. (C) NETosis of neutrophils stimulated with buffer changed saliva from ND and BD patients. (D) NETosis of neutrophils stimulated with saliva from BD patients, mucins resuspended in protein-free saliva from ND patients, and protein-free saliva from BD patients. Representative images are found in supplementary Figure 6. Columns denote average values and error bars standard deviations. N.S., not significant. **P < .01; *** P < .001.