[Expression of adhesion molecules, intercellular molecule (ICAM)-1 and lymphocyte function associated antigen (LFA)-1...

We histochemically examined the expression of adhesion molecules, ICAM-1 and LFA-1, of endothelial cells in the synovial tissues of rheumatoid arthritis. Subjects were 7 RA patients of 1, 3, 4 months and 2, 3, 5, 7 years duration, 2 cases of mixed connective tissue disease (MCTD), both of 5 years duration, and 3 cases of osteoarthritis (OA) 15 years after onset. ICAM-1 was expressed on the cell surface and in the cytoplasm of the endothelial cells of small veins, and in the germinal center of lymphoid follicle, while LFA-1 was expressed on lymphocytes around the small vessels which expressed the ICAM-1 molecule. The most characteristic point of this study was that we adopted not only histochemical but also quantitative methods. At one month from onset, faintly positive ICAM-1 molecules were expressed on endothelial cells accompanied by LFA-1 positive spindle cells, called interstitial cells. Typical high endothelial venules (HEV) with intensive expression of ICAM-1 appeared 3 months after onset. These LFA-1 positive lymphocytes consisted of equal numbers of CD4+ and CD8+ T lymphocytes. There were few B lymphocytes in the synovial tissues in the early stage. The number of small vessels expressing ICAM-1 decreased with the development of the lymphoid follicle, though the intensity of ICAM-1 expressed in each vessel was very high. Our data revealed that ICAM-1 was expressed not only in RA synovia but also in OA which is not ordinarily considered to be immunogenic inflammation, though the molecules were expressed on the flat endothelial cells and not HEV, without accumulation of lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)