Demographic and clinical data analysis
The demographic characteristics of involved patients and healthy controls (HC) were described in Table I. A total of 40 eligible patients with MPO-AAV were enrolled in patient group, among whom 39 were diagnosed as MPA and 1 as GPA. The male patients (60.00%) were more than the females (40.00%). Laboratory tests for p-ANCA and MPO-ANCA in patient group were both positive. Their disease duration was 6.75 ± 6.72 months and their mean BVAS was 21.03±5.97. The HC group also consisted of 40 volunteers with negative test results for both p-ANCA and MPO-ANCA. There was no difference between the 2 group in terms of age (67.65 ± 12.52 vs. 65.30 ± 10.13 years old) and gender ratio (60.00% vs. 47.51% were male), indicating that the 2 groups were comparable demographically.
The difference of PAD4 expression between patient and HC group
The expression of PAD4 in neutrophils detected by FCM was described by the percentage of neutrophils expressed PAD4+ in all neutrophils and the mean fluorescence intensity (MFI) of PAD4+neutrophils. Statistical analysis showed that the percentage of PAD4+ neutrophils in the patient group was significantly higher than that in HC group (70.48 ± 10.47% vs . 25.91 ± 6.33%, p <0.001; Fig.1A). Also, the MFI of PAD4+neutrophils was increased significantly in the patient group compared with the HC group (32.89 ± 4.43 vs. 14.41 ± 4.24,p <0.001; Fig.1B).