Circulating immune complexes in mixed connective tissue disease.
Circulating immune complexes were measured by three assays (monoclonal rheumatoid factor radioimmunoassay, C1q-binding assay, Raji cell radioassay) in sera from patients with mixed connective tissue disease. Evidence for circulating immune complexes was found by at least one method in 94% of sera. The highest frequency of positive results was noted by the Raji cell radioassay (88%). However, a significant number of patients also had immune complexes measured by the C1q-binding assay (50%) and monoclonal rheumatoid factor radioimmunoassay (45%). Further, the levels of immune complexes are measured by the Raji cell radioassay, and to a lesser extent the C1q-binding assay, correlated with disease activity and represent a potentially useful clinical tool. The pattern of reactivity in mixed connective tissue disease sera differed from rheumatoid arthritis, scleroderma, and polymyositis. This suggests that a spectrum of immune complexes is found in these rheumatic diseases and supports the concept that mixed connective tissue disease is distinct from these diseases.
D000974:Antibodies, Antinuclear / Q000032:analysis; D000936:Antigen-Antibody Complex; D005260:Female; D005455:Fluorescent Antibody Technique; D006386:Hemagglutination Tests; D006801:Humans; D007457:Iodine Radioisotopes; D007841:Latex Fixation Tests; D008722:Methods; D008875:Middle Aged; D008947:Mixed Connective Tissue Disease / Q000276:immunology*; D011863:Radioimmunoassay; D012217:Rheumatoid Factor / Q000032:analysis
D000974:Antibodies, Antinuclear; D000936:Antigen-Antibody Complex; D007457:Iodine Radioisotopes; D012217:Rheumatoid Factor