title: Response of circulating immune complexes to food challenge in relapsing IgA nephropathy.
abstract: The response of circulating immune complexes (CIC) to food challenge was assessed in 15 subjects with IgA nephropathy (IgAN) and recurrent macroscopic haematuria. CIC were measured by solid-phase C1q binding assay (SP-C1q), immunoglobulin class-specific polyethylene glycol (PEG) precipitation assays (PEG-G, PEG-A, PEG-M) and by an antigen (ovalbumin)-specific radioimmunoassay after acid dissociation (OA-IC). CIC were measured when the subjects were fasting and hourly for 6 h after a test meal containing eggs. All 15 subjects were tested while clinically quiescent (remission) and 6 were tested again during episodes of macroscopic haematuria (relapse). The PEG-A CIC response to food challenge was significantly exaggerated in IgAN remission compared with controls at 3-6 h after food. There were also non-significant increases in PEG-G, though not in PEG-M. Paired data showed further exaggeration of PEG-G, PEG-A and PEG-M responses to food during IgAN relapse, but significance was not attained if the findings in 1 subject were separated. In this individual a florid clinical relapse with transient decline in renal function was associated with very high levels of PEG-IC, and only in this patient in relapse was OA-IC detectable, confirming that some PEG-precipitated material represented antigen-antibody complexes containing food antigen.
authors.affiliation: Department of Renal Medicine, Manchester Royal Infirmary, UK.
authors.forename: J
authors.initials: J
authors.lastname: Feehally
authors.forename: T J
authors.initials: TJ
authors.lastname: Beattie
authors.forename: P E
authors.initials: PE
authors.lastname: Brenchley
authors.forename: B M
authors.initials: BM
authors.lastname: Coupes
authors.forename: N P
authors.initials: NP
authors.lastname: Mallick
authors.forename: R J
authors.initials: RJ
authors.lastname: Postlethwaite
mesh_terms: D000293:Adolescent; D000328:Adult; D000936:Antigen-Antibody Complex / Q000276:immunology*; D005502:Food; D005922:Glomerulonephritis, IGA / Q000276:immunology*; D006801:Humans
chemical_list: D000936:Antigen-Antibody Complex