DES-LYS(58)-BETA(2)M AND NATIVE BETA(2)M IN RHEUMATOID-ARTHRITIS SERUM AND SYNOVIAL-FLUID

Objective. Levels of beta(2)-microglobin and modified beta(2)-microglo bulin (Des-Ly(58)-beta(2)m) were measured in serum and synovial fluids from patients with rheumatoid arthritis(RA) and other inflammatory jo ints disorders using rabbit antisera prepared against the arn peptide VEHSDLSFS encompassing residues 49-57 and absorbed with the C-terminal beta(2)m peptide (87-97) LSQPKIVKWDR. These antisera which did not re act with native beta(2)m were employed to quantitate Des-Lys(58)-beta( 2)m in serum and SF. Native beta(2)m was measured using a direct ELISA method. Results. Removal of serum rheumatoid factor by adsorption to monomeric IgG columns did not change serum levels of beta(2)m or Des-L ys(58)-beta(2)m. Native beta(2)m was found in all of 20 RA sera, but o nly rarely in SLE sera. No serum beta(2)m was found in 20 patients wit h ankylosing spondylitis or 25 normal controls. Significant elevations of Des-Lys(58)-beta(2)m were found in 80% of 21 SF from RA patients a nd in 43% of 41 SF from other subjects with various forms of inflammat ory arthritis. lit RA and other disorders such as gout or pseudogout, levels of Des-Lys(58)-beta(2)m were higher in synovial fluid than in s erum during an acute episode of synovitis. Both native beta(2)m and De s-Lys(58)-beta(2)m showed minimal neutrophil find T cell chemotactic a ctivity. Conclusion. Des-Lys(58)-beta(2)m present in many inflammatory SF may contribute to the inflammatory reaction irt many forms of conn ective tissue disease by its known amplification of T cell cytotoxicit y.