Original Article Serum under-galactosylated IgA1 is increased in Japanese patients

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 clinicopatho-logical severity of IgAN was then analysed between pa-tients with high and low HAA–IgA binding levels. The levels were also compared in 11 patients before and afte