Figure 5

Histologic analysis of synovial tissue sections from juvenile idiopathic arthritis (JIA) patients. Serial synovial tissue sections from three JIA patients were stained with CD20 (a), CD138 (b), CD21 (c), and CD27 (d) mAbs by using the peroxidase method. CD20⁺ B cells cluster within lymphoid aggregates, whereas CD138⁺ plasma cells localize at the periphery of such aggregates. Staining for CD21, a follicular dendritic cell marker, is negative, consistent with the absence of follicular organization. CD27⁺ cells are found both inside and outside the lymphoid aggregates.