[Beta2 microglobulin, antibeta2 microglobulin activity and circulating immune complexes in rheumatoid arthritis. Serum and synovial study].

In this work, the authors found significantly raised serum Beta2m microglobulin values in a group of 120 cases of rheumatoid arthritis, without any difference between the serum positive group (55 cases) and the serum negative group (65 cases). Such a rise was found in the synovial fluids with a beta2 serum synovial fluid greater than unity in 81 % of cases of rheumatoid arthritis as against 6 % in a control group. The comparative study and the main immunological disorders permits one to note a correlation between the levels of circulating immune complexes (CIC) fixing the Clq and the serum beta2m in serum negative cases of rheumatoid arthritis (RA) (r = 0.52 p < 0.001) whereas this link does not exist in the serum positive group (r = 0.08). These conclusions led the authors to an anti-serum beta2m activity in the serum positive and negative groups of RA, which were very significantly different from the control groups. Furthermore, a study of complement activation, by titration of C3d showed a significant correlation between the levels of CIC and of C3d in RA -, but not in RA +. The authors discuss the participation of beta2m in the formatiton of CIC during RA and its role in the activation of complement.