title: Spectrotype distributions of circulating IgG from patients with systemic lupus erythematosus.
abstract: Pathogenic autoantibodies from patients with systemic lupus erythematosus (SLE) may represent a relatively cationic fraction of IgG. We compared the spectrotype distributions of affinity-purified IgG from the sera of 10 SLE patients and 10 age- and sex-matched control subjects. Purified IgG was subjected to isoelectric focusing between pI 3 and 9. No significant difference was observed for pI 6.0-6.5 and 7.5-8.0. However, control subjects had a higher percent of total IgG at 6.5-7.0 (15.4 +/- 4.0 vs 11.1 +/- 2.0, P = 0.008) and at 7.0-7.5 (22.4 +/- 4.8 vs 18.2 +/- 3.8, P = 0.04) whereas SLE patients had a higher percent of total IgG at 8.0-8.5 (24.3 +/- 3.0 vs 20.5 +/- 4.0, P = 0.03) and at 8.5-9.0 (21.9 +/- 5.9 vs 15.1 +/- 3.7, P = 0.006). Spectrotype distributions of circulating IgG from SLE patients are skewed toward higher pI, providing further evidence of proliferation of B-cell clones that express more cationic IgG in patients with SLE. Longitudinal studies of serum IgG from several patients for > 1 year reveal distinct changes in both cationic and anionic clonotypes, suggesting clonal expansion of antiidiotypes to autoantibodies.
authors.affiliation: Rheumatology Laboratory, St. Joseph's Hospital and Medical Center, Paterson, NJ 07503.
authors.forename: G
authors.initials: G
authors.lastname: Barbi
authors.forename: L B
authors.initials: LB
authors.lastname: Keil
authors.forename: A D
authors.initials: AD
authors.lastname: Gaito
authors.forename: V A
authors.initials: VA
authors.lastname: DeBari
mesh_terms: D001323:Autoantibodies / Q000097:blood*; D015658:HIV Infections / Q000276:immunology; D006801:Humans; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000097:blood*; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D007074:Immunoglobulin G