Table 3.

Histological severity grade of RA synovia and incidence of CIT-013 staining.

Biopsy	Histological severity grade	Key histological features	Incidence of CIT-013 staining	Histological localization of CIT-013 staining
1	No active synovitis	Quiescent synovium with a few scattered inflammatory cells within connective tissue	Occasional positive punctate cells	Infiltrating acute cells
2*	Minimal synovitis	Scattered lymphoid foci and scattered mixed inflammatory infiltrate, cartilage and bone admixed with the synovial matrix	Minimal diffuse staining, occasional positive punctate cells	Infiltrating acute cells
3	Minimal active synovitis	Focal areas of synovial hyperplasia with diffuse inflammatory infiltrates in the sub-lining	Minimal diffuse staining, occasional positive punctate cells	Infiltrating acute cells
4	Minimal reactive synovitis	Low-grade acute synovitis with a low-grade fibrogranular reaction around detritic foci, and low-grade acute inflammatory infiltrate around microvasculature	Occasional positive punctate cells	Infiltrating acute cells
5*	Moderate active synovitis	Lymphoid foci with microvascular sinusoid formation, hyperplastic synovial lining with zones of lymphoid, mononuclear and macrophage infiltration in sub-lining, peri-vascular acute inflammatory infiltrates, and diffuse stromal cell reaction	Moderate to marked multi-focal staining	Synovial lining, sub-lining, peri-vascular, peri-lymphoid, and demarcation of follicular zones
6*	Moderate to marked active immune synovitis	Marked lymphoid-rich (follicular) synovitis, multiple lymphoid foci with abundant microvascular sinusoid formation, markedly hyperplastic synovial lining with dense zones of lymphoid, mononuclear and macrophage infiltration in sub-lining, peri-vascular acute inflammatory infiltrates, and diffuse stromal cell reaction	Marked zonal staining	Synovial lining, sub-lining, peri-vascular, peri-lymphoid, and demarcation of follicular zones

*These biopsies are demonstrated in Figure 1.