title: Palisading cells of rheumatoid nodules: comparison with synovial intimal cells.
abstract: OBJECTIVE
  The palisading cells of rheumatoid nodules share certain features with synovial intimal cells. The similarities between the two cell populations have been reassessed using new cytochemical markers.
  
  
  METHODS
  Cell populations in cryostat sections of non-inflamed, rheumatoid and osteoarthritic synovial tissues, and rheumatoid nodules were assessed for the presence of CD68, prolyl hydroxylase, vascular cell adhesion molecule 1 (VCAM-1), and the alpha 4 and beta 1 integrin chains, and the activity of uridine diphosphoglucose dehydrogenase (UDPGD) and nonspecific esterase.
  
  
  RESULTS
  Synovial intimal cells formed a dual population of macrophages (nonspecific esterase positive, strongly positive for CD68) and fibroblastic cells (prolyl hydroxylase positive). The latter showed prominent VCAM-1 expression and high UDPGD activity as previously reported and also prominent beta 1 integrin chain expression. Palisading cells similarly proved to be a dual population of macrophages and fibroblastic cells. In contrast with synovial intima, however, the fibroblastic cells lacked UDPGD activity and expression of VCAM-1 and showed no preferential expression of the beta 1 integrin chain. The exception to this rule was where nodules contained central clefts, which were lined with cells showing all the features associated with synovial intimal cells.
  
  
  CONCLUSIONS
  Palisading cells are a mixture of macrophages and fibroblasts, but the latter show no evidence of synoviocyte differentiation. Cells with features of synoviocytes may occur lining clefts within areas of necrobiosis.
authors.affiliation: Division of Rheumatology, University College London Medical School, United Kingdom.
authors.forename: J C
authors.initials: JC
authors.lastname: Edwards
authors.forename: L S
authors.initials: LS
authors.lastname: Wilkinson
authors.forename: A A
authors.initials: AA
authors.lastname: Pitsillides
mesh_terms: D015703:Antigens, CD / Q000032:analysis; D015214:Antigens, Differentiation, Myelomonocytic / Q000032:analysis; D001172:Arthritis, Rheumatoid / Q000473:pathology; D043182:Carboxylesterase; D002265:Carboxylic Ester Hydrolases / Q000032:analysis; D015815:Cell Adhesion Molecules / Q000032:analysis; D005347:Fibroblasts / Q000473:pathology; D006801:Humans; D016023:Integrins / Q000032:analysis; D008264:Macrophages / Q000201:enzymology / Q000473:pathology; D010003:Osteoarthritis / Q000473:pathology; D012218:Rheumatoid Nodule / Q000378:metabolism / Q000473:pathology*; D013583:Synovial Membrane / Q000473:pathology*; D014533:Uridine Diphosphate Glucose Dehydrogenase / Q000378:metabolism; D019010:Vascular Cell Adhesion Molecule-1; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D043182:Carboxylesterase; D002265:Carboxylic Ester Hydrolases; D015815:Cell Adhesion Molecules; D016023:Integrins; D014533:Uridine Diphosphate Glucose Dehydrogenase; D019010:Vascular Cell Adhesion Molecule-1; C067980:CD68 antigen, human; D000097382:CD68 Molecule