title: Characterization of circulating immune complexes detected by monoclonal rheumatoid factor and conglutinin radioimmunoassays in SLE nephritis.
abstract: By utilizing a monoclonal rheumatoid factor (mRF) and bovine conglutinin (K) in radioimmunoassays, ICs detected in sera of patients with lupus nephritis were partially characterized. The mRF-RIA detected high levels of ICs in 86.9% of patients with active SLE and in only 22.7% of patients with inactive disease. Positive association was observed with clinical scores and significant negative correlation was found with serum levels of C1q, C3 and C4. The mRF-reactive ICs were shown to be cryoprecipitable and analysis by gel filtration through Sephacryl S-300 disclosed a material eluting between IgM and IgG, being dissociated in acidic pH. On the other hand, no association could be demonstrated between levels of ICs detected by K-RIA and clinical activity. Positivity in this assay was only 8.7% and 31.8% for active and inactive groups. Differently from the ICs detected by mRF-RIA, the K-reactive material was not precipitated by 3.5% PEG, nor by centrifugation in the cold, and EDTA did not reduce the binding of IgG to K in positive sera. The reactive IgG in Sephacryl S-300 chromatography eluted in the same position as monomeric IgG both in neutral and dissociating conditions. No C3 could be detected in ICs reactive in both assays.
authors.affiliation: Disciplina de Nefrologia--Escola Paulista de Medicina, São Paulo, Brasil.
authors.forename: S K
authors.initials: SK
authors.lastname: Nishida
authors.forename: M A
authors.initials: MA
authors.lastname: Alves
authors.forename: O L
authors.initials: OL
authors.lastname: Ramos
authors.forename: A B
authors.initials: AB
authors.lastname: Pereira
mesh_terms: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex / Q000032:analysis*; D037222:Collectins; D003168:Complement Fixation Tests; D003165:Complement System Proteins / Q000032:analysis; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D008181:Lupus Nephritis / Q000276:immunology*; D011863:Radioimmunoassay; D012217:Rheumatoid Factor / Q000032:analysis; D012712:Serum Globulins / Q000032:analysis
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D037222:Collectins; D007074:Immunoglobulin G; D012712:Serum Globulins; C024014:conglutinin; D003165:Complement System Proteins; D012217:Rheumatoid Factor