Sialyl Lewis(x) expression on IgG in rheumatoid arthritis and other arthritic conditions: a preliminary study

Both infiltrating leukocytes and soluble immunoglobulin form aggregates in synovial fluid during the inflammatory process in rheumatoid arthritis (RA) . Some of these changes are probably mediated by the adhesion molecule, E-s electin, which increases its expression with disease activity. As glycosyla tion changes in IgG in RA are well established, the current study was under taken to measure the expression of the carbohydrate antigen sialyl Lewis x (sLe(x)), on IgG in RA. sLe(x) is a major ligand for E-selectin. Using a re cently developed ELISA, sLe(x) expression was determined in IgG isolated fr om 8 healthy individuals, 20 RA sufferers (10 early and 10 with more long-s tanding disease) and 20 patients with other rheumatic conditions (osteoarth ritis, ankylosing spondylitis, systemic lupus erythematosus). S Le(x) expre ssion on IgG was elevated above the reference range in all but one of the R A patients and this change was highly significant (P < 0.0006). Expression of this antigen on IgG was also significantly different from normal in the other arthritic groups (P < 0.02), but the changes were much less than that observed for RA. In early RA, sLe(x) was inversely correlated with paramet ers used to measure disease activity. This was not observed with the establ ished RA, where there was weak positive association. These preliminary resu lts indicate that a change in sLe(x) expression on IgG is an early finding in the development of RA, which may be important in the development of the disease or for predicting its outcome.