Figure 2  .

Immunostaining of sample tissues from RA patients (a-d) and MRL/Mp-lpr/lpr mouse (e). The staining for TRAP was performed according to the method of Burstone.²¹ Immunostaining was done as described in figure 1, using mouse monoclonal antibody against human CD68 (Dako, Denmark), HLA-DR (Dako, Denmark), and leucocyte T cell (MT1, Bio-science products, Switzerland). (a) Islands (arrows) that invaded into the deep zone of articular cartilage (AC) through the calcified cartilage from the subchondral bone (SB). TRAP positive multinucleated cells (arrowhead); (b) CD68 positive cells; (c) MT-1 positive cells; (d) HLA-DR positive cells in islands and subchondral bone. (e) TRAP positive multinucleated cells (arrows) beneath undamaged AC preceding remarkable inflammation of the synovial membrane (SM). ((a) Original magnification × 13.2, (b) original magnification × 66, (c) to (e) original magnification × 132).