title: Reduced synovial membrane macrophage numbers, ELAM-1 expression, and lining layer hyperplasia in psoriatic arthritis as compared with rheumatoid arthritis.
abstract: OBJECTIVE
  To define the immunohistologic features of the synovial membrane (SM) of patients with psoriatic arthritis (PA) and to compare them with those of an age- and disease-duration-matched population of patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Synovial membrane needle biopsy was performed on 15 PA patients with knee involvement (8 had asymmetric oligoarthritis and 7 had symmetric polyarthritis) and on 15 RA controls. Specimens were stained with monoclonal antibodies against T cells (CD3, CD8, CD4, CD45RO), B cells (CD20), macrophages (Mac387, CD14), and cells bearing class II antigens (DAKO-DR). Vascular endothelium was examined using a polyclonal antibody to Factor VIII-related antigen, and adhesion molecule expression was examined using antibodies 1.3B6, 6.5B5, and 1.4C3, which identify endothelial leukocyte adhesion molecule 1 (ELAM-1), intercellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1), respectively.
  
  
  RESULTS
  There was significantly less lining layer hyperplasia, fewer macrophages, and a greater number of blood vessels in PA SM than in RA SM: ELAM-1 expression was less intense in PA than in RA SM, while there was no difference in expression of ICAM-1 and VCAM-1. Numbers of B cells, T cells, and T cell subsets (predominantly CD4, CD45RO T cells) were similar in both groups of patients.
  
  
  CONCLUSIONS
  Our findings demonstrate important differences in the immunohistologic features of PA and RA SM: The PA SM is more vascular, ELAM-1 expression is less intense, and fewer macrophages invade the stroma and migrate to the lining layer than in RA SM: However, the lymphocytic infiltrate in the SM of both groups is similar.
authors.affiliation: St. Vincent's Hospital, Dublin, Ireland.
authors.forename: D
authors.initials: D
authors.lastname: Veale
authors.forename: G
authors.initials: G
authors.lastname: Yanni
authors.forename: S
authors.initials: S
authors.lastname: Rogers
authors.forename: L
authors.initials: L
authors.lastname: Barnes
authors.forename: B
authors.initials: B
authors.lastname: Bresnihan
authors.forename: O
authors.initials: O
authors.lastname: Fitzgerald
mesh_terms: D000328:Adult; D000368:Aged; D015535:Arthritis, Psoriatic / Q000473:pathology*; D001172:Arthritis, Rheumatoid / Q000473:pathology*; D015704:CD4 Antigens / Q000032:analysis; D015815:Cell Adhesion Molecules / Q000032:analysis*; D002452:Cell Count; D019040:E-Selectin; D004730:Endothelium, Vascular / Q000737:chemistry; D005260:Female; D006801:Humans; D006965:Hyperplasia; D007150:Immunohistochemistry; D017493:Leukocyte Common Antigens / Q000032:analysis; D008264:Macrophages / Q000737:chemistry / Q000473:pathology*; D008875:Middle Aged; D013583:Synovial Membrane / Q000473:pathology*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D015704:CD4 Antigens; D015815:Cell Adhesion Molecules; D019040:E-Selectin; D017493:Leukocyte Common Antigens