NEPHELOMETRIC STUDY OF THE REACTION OF MONOCLONAL RHEUMATOID-FACTOR WITH HEAT AGGREGATED GAMMA-GLOBULIN AND SERA FROM PATIENTS WITH IMMUNE-COMPLEX DISEASES

Abstract

Monoclonal rheumatoid factors (MCRF) were used in a variety of assays for the detection of Ig[immunoglobulin]G-containing circulating immune complexes. A MCRF was isolated from a patient with a lymphoproliferative disorder and a nephelometric technique was used to characterize its reaction with heat-aggregated .gamma.-globulin (HAGG) used as a source of artificial immune complexes. The method is simple, economical and rapid and can detect 6 .mu.g/ml of HAGG over a wide range of physicochemical conditions. The sera from 35 of 58 patients (59%) with rheumatoid arthritis and 21 of 74 patients (28%) with systemic lupus erythematosus (SLE) gave increased precipitation with MCRF compared with 232 blood donors. Sucrose gradient ultracentrifugal analysis of 9 strongly precipitating sera revealed that in 8, the MCRF precipitated with material sedimenting in the monomeric IgG position. In only 1 specimen the MCRF reacted with material sedimenting in heavier regions. Different MCRF may vary in the specificity for binding IgG complexes. These reagents should be carefully characterized before becoming established in nephelometric assays for circulating immune complexes.