1992 Volume 15 Issue 3 Pages 246-253
In 42 systemic lupus erythematosus (SLE) patients, the plasma levels of circulating immune complexes (CIC) and four kinds of complement derived product (Bb, C 4 d, iC 3 b and C 5 b-9) were examined to evaluate their usefulness in monitoring disease activity of SLE.
CIC levels were measured by two different enzyme linked immunosorbent assays (ELISA), (1) anti-C 3 d antibody method (C 3 dCIC) and (2) solid phase C 1 q binding method (C 1 qCIC). The levels of complement derived products were also measured by ELISA using monoclonal antibodies to each product. At the initiation of this study, 5 patients were considered to be active according to our criteria.
The following results were obtained: (1) The incidence of elevated plasma levels of C 3 dCIC, C 1 qCIC, Bb, C 4 d, iC 3 b and C 5 b-9 was 21.4%, 45.2%, 16.7%, 38.1%, 85.7% and 64.2%, respectively. C 3 dCIC was positive in all 5 patients with active disease, and C 1 qCIC was positive in 4 of these 5 patients. (2) The plasma levels of C 3 dCIC, Bb and C 5 b-9 had statistically significant correlation with anti DNA antibody titers, and had inverse correlation with values of CH 50 and serum concentrations of both C 3 and C 4. However, there was no significant correlation between the C 1 qCIC levels and any of these conventional parameters of lupus activity. (3) The mean plasma levels of C 3 dCIC, Bb and C 5 b-9 were significantly higher in active group than those in inactive group. (4) In one longitudinally followed patient, elevation of C 3 dCIC occurred correlated with flares of SLE. The levels of C 5 b-9 also varied in accordance with lupus activity, however, they continued to remain rather high after the disease activity was controlled. In conclusion, measurement of plasma levels of C 3 dCIC and C 5 b-9 is considered to be useful for evaluating disease activity of patients with SLE.
