Immunohistochemical staining of primary-culture RA synovial cells in chamber slides: (A), (B), (D)-(H) phase contrast, and (C) lightfield. While (A) control isotype-matched mAbs (peroxidase) or (B) rabbit serum (APAAP) showed no positive reaction, (C) the anti-Thy-1 mAb AS02 stained large, flat, spindle-shaped or stellate-shaped cells (ie cells with FB morphology; alkaline phosphatase, purple staining) and (D) the anti-CD14 mAb RMO52 identified small, round cells, conceivably macrophages (peroxidase, brown staining). The RA-SFB clearly expressed (E) procollagen I and (H) procollagen III (APAAP, red staining). The primary culture contained no endothelial cells, as documented by the lack of staining for (F) von Willebrand factor (APAAP) and (G) CD144 (APAAP). Original magnification: (A), (B), (F), and (G), 184 ×; (C)-(E) and (H) 368 ×.