Fig. 1

a–g IHC staining for CD68/CD21 on ST of patients with naïve or MTX-IR PsA and Ab^neg RA patients. Example photos of CD68 (RED)/CD21(DAB) staining of ST biopsies from patients with naïve (a) or MTX-IR (b) PsA patients and with naïve (c) or MTX-IR (d) Ab^neg RA (magnification × 20 and magnification × 40 in the corresponding inset). Black arrows indicate CD68⁺ cells (red), and black arrow head indicates CD21⁺ cells (brown) in the corresponding inset. e Lining IHC score for CD68⁺ cells in PsA and Ab^neg RA patients divided by treatment regimen. f Sublining IHC score for CD68⁺ cells in PsA and Ab^neg RA patients divided by treatment regimen. g IHC score for CD21⁺ cells in PsA and Ab^neg RA patients divided by treatment regimen. IHC immunohistochemistry, PsA psoriatic arthritis, RA rheumatoid arthritis, Ab autoantibody, MTX-IR methotrexate inadequately responder, CD cluster designation