Immunohistochemical detection of lymphocytes in N/R (A and C) and in I (B and D) synovial biopsies. At the time of surgery, synovial biopsies coming from N/R or I areas were macroscopically selected as described in Materials and methods. Immunohistochemical staining of lymphocytes was performed using anti CD45 antibody. Positive staining was detected as brown peroxidase reaction product. (A) and (B) Global image of the section → intima linning, ⇒ lymphoid node (C) and (D) magnification (×100) of intima lining.