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

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.

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.

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).

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