Distribution in human tissues of the synovial lining-associated epitope recognised by monoclonal antibody 67.

Murine monoclonal antibody Mab 67 was originally shown on histochemical screening to bind to synovial intimal fibroblasts (SIF), cells in lymphoid follicles and elastic fibres. As part of a programme to isolate the antigen recognised by Mab 67 and determine its function, a wider histochemical study was performed. Cryostat sections were prepared from normal human adult synovium, skin, placenta, amnion, kidney, tonsil, breast, thyroid, colon and pericardium, fetal limb tissues and rheumatoid arthritic synovium. Sections were stained with Mab 67, anti-CD3, as isotype matched control, and anti-VCAM-1 using alkaline phosphatase -anti-alkaline phosphatase. Selected sections were double labelled for nonspecific esterase activity. Staining by Mab 67 of SIF, identified as NSE-negative intimal cells, and follicle centre cells was confirmed. Staining with Mab 67 was also seen on Bowman's capsule and juxtaglomerular apparatus, stratum granulosum of skin, pulmonary alveolar cells, amniotic epithelium, chorionic villi, fetal synovium, bone marrow stromal cells and epidermis, and interstitial elastic fibres in most tissues, but not at other sites in these tissues or in pericardium, muscle, colon, breast, thyroid, salivary gland or vein. The staining pattern with Mab 67 suggests that the antigen is pericellular. Its distribution does not match any molecule known to us but overlaps at several sites with VCAM-1 (SIF, follicle centres, Bowman's capsule and bone marrow stroma). We suggest that the antigen involved may possible by similarly involved in cell-matrix interaction.