Serum under-galactosylated IgA1 is increased in Japanese patients with IgA nephropathy

Nephrol Dial Transplant. 2008 Jun;23(6):1931-9. doi: 10.1093/ndt/gfm913. Epub 2008 Jan 4.


Background: Immunoglobulin A nephropathy (IgAN) is characterized by an aberrant structure of O-glycans in the IgA1 hinge region. Recently, under-galactosylated IgA1 has been found to be increased in Caucasian IgAN patients. Thus, we examined this in Japanese IgAN patients.

Methods: An enzyme-linked immunosorbent assay of binding between Helix aspersa (HAA) and serum IgA was performed in Japanese IgAN patients and the HAA-IgA binding levels were compared among IgAN patients (n = 41), patients with other forms of kidney disease (OKD, n = 43) and healthy controls (n = 38). The clinicopathological severity of IgAN was then analysed between patients with high and low HAA-IgA binding levels. The levels were also compared in 11 patients before and after the combination of tonsillectomy and steroid pulse therapy. Furthermore, we examined the O-glycan structure of IgA1 hinge glycopeptides by mass spectrometry (MS).

Results: The HAA-IgA binding levels were significantly higher in IgAN patients compared with either healthy controls (P = 0.0025) or those with OKD (P = 0.016). To reflect the absolute level of under-galactosylated IgA, we multiplied the HAA-IgA binding level by the serum IgA concentration to produce an indicative value. The specificity and sensitivity of this value were 89% and 66%, respectively. MS showed that peak distribution of IgA1 hinge glycopeptides was shifted to smaller molecular weights in high HAA-IgA-binding IgAN patients. There was no correlation between the HAA-IgA binding level and either disease severity or the use of combination therapy.

Conclusions: HAA-IgA binding is significantly increased in Japanese IgAN patients. This potential IgAN marker is not affected by disease severity or therapeutic intervention.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers / blood
  • Case-Control Studies
  • Cohort Studies
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Glomerulonephritis, IGA / blood*
  • Glomerulonephritis, IGA / diagnosis*
  • Glycosylation
  • Humans
  • Immunoglobulin A / blood*
  • Japan
  • Kidney Diseases / blood
  • Kidney Diseases / diagnosis
  • Kidney Function Tests
  • Male
  • Middle Aged
  • Pilot Projects
  • Prognosis
  • Reference Values
  • Sensitivity and Specificity
  • Severity of Illness Index


  • Biomarkers
  • Immunoglobulin A