Expression of vascular cell adhesion molecule-1 in normal and inflamed synovium.
BACKGROUND
The intercellular adhesion molecule vascular cell adhesion molecule-1 (VCAM-1) has been implicated in a number of interactions between leukocytes and cells of lymphoid and connective tissue, including endothelial cells. Such interactions within synovial tissue may be important in the pathogenesis of rheumatoid arthritis.


METHODS
The expression of VCAM-1 on specific cell populations in normal and inflamed synovium was investigated using a range of double-labeling techniques.


RESULTS
The strongest VCAM-1 staining was found to be confined to four nonmacrophage populations (as judged in terms of CD68 expression, nonspecific esterase activity, content of prolyl hydroxylase and activity of uridine diphosphoglucose dehydrogenase): (i) type B synoviocytes, (ii) vascular wall cells outside the endothelial layer, (iii) scattered stromal cells with cytoplasmic processes, and (iv) cells resembling follicular dendritic reticulum cells in lymphoid aggregates with germinal centers (in the three samples of rheumatoid arthritic tissue where these were present). Some macrophages of the synovial intima showed weak VCAM-1 staining. Endothelial cell staining was seen but it was consistently weaker than the staining of cells of group ii.


CONCLUSIONS
The four cell populations described as showing bright staining for VCAM-1 may all be involved in local interactions with leukocytes of the macrophage or lymphoid series subsequent to initial leukocyte entry into the tissue. Expression of VCAM-1 by these cells may play a role in such interactions.
Wilkinson
L S
LS
Department of Medicine, Royal Postgraduate Medical School, London.
Edwards
J C
JC
Poston
R N
RN
Haskard
D O
DO
D001172:Arthritis, Rheumatoid / Q000378:metabolism / Q000473:pathology; D043182:Carboxylesterase; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D010003:Osteoarthritis / Q000378:metabolism / Q000473:pathology; D012016:Reference Values; D013194:Staining and Labeling; D013583:Synovial Membrane / Q000378:metabolism* / Q000473:pathology; D013585:Synovitis / Q000378:metabolism* / Q000473:pathology; D014018:Tissue Distribution; D014533:Uridine Diphosphate Glucose Dehydrogenase / Q000378:metabolism; D019010:Vascular Cell Adhesion Molecule-1
D015815:Cell Adhesion Molecules; D019010:Vascular Cell Adhesion Molecule-1; D014533:Uridine Diphosphate Glucose Dehydrogenase; D002265:Carboxylic Ester Hydrolases; D043182:Carboxylesterase