title: Clonally restricted anti-IgG antibodies in rheumatoid arthritis.
abstract: Clonally restricted anti-IgG antibodies were detected, by isoelectric focusing (IEF) and chromatofocusing techniques, in the sera of patients with rheumatoid arthritis (RA). Anti-Fab antibodies were predominantly acidic proteins with isoelectric points of 4.5-6.5 and displayed restricted spectrotype patterns. Proteins reactive with the Fc portion of IgG showed polyclonal spectrotype patterns with alkaline pI of 7.5-9.0. A limited array of anti-Fab spectrotypes was consistently detected in RA sera when analyzed by IEF on 6M urea gels. Additional anti-Fab antibody bands were detected when the RA sera were dialyzed against 4-6M urea prior to IEF analysis, indicating that some anti-Fab antibodies exist in a complexed form in serum. Under these dissociating conditions, anti-Fab antibodies could also be detected in normal subjects, but the spectrotype patterns were more restricted than those in RA sera. Because anti-Fab antibodies may regulate normal immune responses, the increased quantity of clonally restricted anti-Fab antibodies in RA may indicate an abnormality of this immunoregulation.
mesh_terms: D000888:Antibodies, Anti-Idiotypic / Q000235:genetics*; D000918:Antibody Specificity; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001798:Blood Proteins / Q000302:isolation & purification; D005591:Chemical Fractionation; D002845:Chromatography; D002999:Clone Cells; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology*; D007525:Isoelectric Focusing; D011485:Protein Binding; D014508:Urea / Q000494:pharmacology
chemical_list: D000888:Antibodies, Anti-Idiotypic; D001798:Blood Proteins; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D014508:Urea