Peripheral B-cell activation and exhaustion markers in patients with ankylosing spondylitis.

Aims: Ankylosing spondylitis (AS) is an autoimmune disease and is associated with abnormal B cell function. However, the roles of different B cell subsets are less clear. This study aimed to examine the frequency of different subsets of B cells in AS patients following standard therapies.

Main Methods: Eighteen newly diagnosed AS patients and 10 healthy controls (HC) were recruited in this study. The expression of CD27, CD38, CD86, CD95 and IgD on CD19(+) B cells was examined by flow cytometry. The disease activity was scored according to the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). Serum levels of C-reactive protein (CRP), rheumatoid factor (RF), IgG, IgA and IgM, and the erythrocyte sedimentation rate (ESR) were measured.

Key Findings: The frequency of CD27(+) B cells was decreased in AS patients compared with HC (p=0.018), while CD86(+) and CD27(-)CD95(+) B cell subsets increased in AS patients (p<0.001). Meanwhile, the frequencies of CD38(+) and CD95(+) B cell positively correlated with BASDAI (r=0.6505, p=0.0035; r=0.6854, p=0.0017, respectively), while CD38(-)CD86(+) B cell negatively correlated with BASDAI (r=-0.7329, p<0.001). We also found that CD27(-) and CD95(+) B cell negatively correlated with RF levels (r=-0.5141, p=0.0290; r=-0.4944, p=0.0370, respectively), while CD27(+) B cell positively correlated with IgG levels (p=0.0148, r=0.5640). Moreover, CD86(+) and CD27(-)CD95(+) B cell subsets increased following treatment with Meloxicam and Etanercept for one month (p<0.001; p<0.001).

Significance: These findings suggest that CD27(-)CD95(+)CD19(+) and CD86(+)CD19(+) B cells may be reasonable cellular targets for the therapeutic intervention of AS.