Ectopic Lymphoid Structures Support Ongoing Production of Class-Switched Autoantibodies in Rheumatoid Synovium
Figure 1
AID Expression within the Rheumatoid Synovial Membrane Is Restricted to Lymphoid Aggregates with FDC Networks
A representative example of sequential paraffin-embedded sections of LN and RA synovial membrane stained for AID (brown, A, E, I), T cells (CD3, brown, B, F, J), B cells (CD20, red, C,G, K) and follicular DCs (CD21, red, D,H, L). The presence of FDC networks was invariably associated with the expression of AID even in FDC+ grade 3 aggregates (arrow, A), without morphologically detectable dark and light zones within the B cell rich area (A−D). In more organised grade 3 aggregates (E−H), expression was more prominent and closely resembled that seen in secondary lymphoid organs, such as the LN (I−L) (original magnification was 20×). Scale bars 200 μm.