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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.