title: Association of IgG co-deposition with serum levels of galactose-deficient IgA1 in pediatric IgA nephropathy.
abstract: OBJECTIVE
  To determine whether the absence of mesangial IgG deposits is associated with the absence of elevated blood levels of galactose-deficient IgA1 (Gd-IgA1) in pediatric patients with IgA nephropathy (IgAN).
  
  
  METHODS
  Serum Gd-IgA1 levels were determined by ELISA using an N-acetylgalactosamine-specific lectin from Helix aspersa. Levels of Gd-IgA1 above the 90th percentile for healthy pediatric controls were considered to be elevated. Renal biopsy samples were examined by immunofluorescence for presence and intensity of staining for IgA, IgG, IgM, C3 and C1q and by light microscopy for histological changes. Findings were graded by a single pathologist (L. Gaber) at UTHSC until 2007 and by NephropathTM (Little Rock, AR, USA) thereafter. Staining for the mesangial deposits was considered negative when intensity was trace or less, and positive at greater intensity. Fisher's exact test was used to determine significance of 2 × 2 tables.
  
  
  RESULTS
  Serum samples were obtained from 30 patients with IgAN diagnosed before age 18 years. Male:female ratio was 2.3:1. Twenty were Caucasian and 10 were African-American. Blood was obtained within 3 months of biopsy (incident cases) for 12, while 18 provided blood > 3 months after biopsy (prevalent cases). Serum Gd-IgA1 level was elevated in 23 (77%) of cases and 20 (67%) had a biopsy positive for IgG. Of those 20 patients, 18 (90%) had an elevated serum Gd-IgA1 level, whereas 5 (50%) of patients with biopsies without IgG had a normal serum Gd-IgA1 level (p = 0.026).
  
  
  CONCLUSIONS
  In this small study we found a weak association between the absence of IgG in the biopsy and normal serum Gd-IgA1 level.
authors.affiliation: University of Tennessee Health Science Center, Le Bonheur Children's Hospital, Memphis, TN, USA.
authors.forename: T Matthew
authors.initials: TM
authors.lastname: Eison
authors.forename: M Colleen
authors.initials: MC
authors.lastname: Hastings
authors.forename: Zina
authors.initials: Z
authors.lastname: Moldoveanu
authors.forename: John T
authors.initials: JT
authors.lastname: Sanders
authors.forename: Lillian
authors.initials: L
authors.lastname: Gaber
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Walker
authors.forename: Keith K
authors.initials: KK
authors.lastname: Lau
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Julian
authors.forename: Jan
authors.initials: J
authors.lastname: Novak
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Wyatt
mesh_terms: D000293:Adolescent; D001706:Biopsy; D002648:Child; D005260:Female; D005455:Fluorescent Antibody Technique; D005690:Galactose / Q000172:deficiency*; D005922:Glomerulonephritis, IGA / Q000276:immunology* / Q000473:pathology; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood*; D007668:Kidney / Q000473:pathology; D008297:Male
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D005690:Galactose