Decreased levels of T follicular helper (CD4+CXCR5+) cells and CD27+CD38+and CD27+CD38-B cells in ankylosing spondylitis patients correlate with markers of inflammation

The purpose of this study was to study CD4+CXCR5+ T follicular helper (TFH) cells, CD27+CD38+ plasmablasts and CD27+CD38- memory B cells, as well as disease-related factors in patients with ankylosing spondylitis (AS) from northern Sweden. Peripheral blood mononuclear cells (PBMC) from 50 patients with AS (mean age 52 +/- 9 years, 66% men, 100% HLA-B27 positive) and 50 pairwise matched blood donor controls (mean age 54 +/- 9 years, 66% men) were stained with antibodies for CD27, CD38, CD19, CD3, CD4 and CXCR5 markers and analysed by flow cytometry. Patients with AS were examined with spinal x-ray for radiographic alterations (mSASSS), and plasma levels of C-reactive protein, erythrocyte sedimentation rate, as well as selected proinflammatory and regulatory cytokines were determined. Physical mobility, function and disease activity were registered by BASMI, BASFI and ASDAS-CRP, BASDAI, respectively. Comparing AS patients and controls pairwise, we observed a 56% reduction of TFH cells in PBMCs from AS patients (P = .000008). Furthermore, a 20%-30% reduction in plasmablasts and B memory cells (P <= .002 and P <= .007, respectively) was observed. In female patients, negative correlations between ESR and TFH, plasmablasts and B memory cells were observed; Rs = -0.551, P <= .02; Rs = -0.476, P <= .05 and Rs = -0.522, P <= .03, respectively. In addition, positive correlations between the regulatory cytokine IL-10 and the proportion of B cells, IL-22, and the proportion of plasmablasts as well as a negative correlation between levels of the proinflammatory cytokine IL-6 and TFH were detected. Our observations indicate a role of an aberrant humoral immune response related to inflammation in AS.