Reactivity of Glomerular and Serum lgA1 to Jacalin in IgA Nephropathy

Abstract

To analyze O-linked oligosaccharides (O-glycans) in the hinge region of IgAl in IgA nephropathy (IgAN), the reactivity of IgA1 to jacalin, which specifically binds to O-glycans, was investigated. Initially, renal biopsy specimens from 5 patients with IgAN and 3 patients with other renal diseases were investigated in an immunofluorescence study with jacalin, monoclonal antihuman IgAl and IgA2 antibodies. All of the renal biopsy specimens of IgAN and none of other renal diseases were positively stained by both FITC-labeled jacalin and monoclonal anti-IgA1 antibody. The glomerular staining patterns of FITC-jacalin were similar to those of the monoclonal anti-IgA1 antibody. IgA2 was negative in all specimens. Based on the positive reactivity of deposited IgA1 to jacalin, the binding ability of serum IgA1 to jacalin was evaluated by inhibition assay using D-galactose in patients with IgAN (n = 58), other primary glomerulonephritides (PGN) (n = 41), and healthy controls (n = 52). The frequencies of the patients with serum IgA1 having a high affinity for jacalin were significantly greater in IgAN (19/58, 32.8%) compared with the healthy controls (2/52, 3.8%) and other PGN (4/41, 9.8%). These results suggested that the increased reactivity of O-glycan(s) in the IgAl hinge region to jacalin is due to an unusual glycosylation of serum IgA1 in IgAN.

Protective role of anti-synthetic hinge peptide antibody for glomerular deposition of hypoglycosylated IgA1

“…There have been many reports on the presence of an incompletely glycosylated O-linked oligosaccharide(s) on the IgA1 hinge region in some IgAN patients [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Previously, we confirmed that enzymatically under-glycosylated IgA1 accumulated in rat glomeruli [20].…”

“…Further, human IgA1 molecules have a unique glycosylated hinge that possesses O-glycan side chains [3]. There are many reports on the presence of an incompletely glycosylated O-linked oligosaccharide(s) in the IgA1 hinge region in some IgAN patients [4][5][6][7][8][9][10][11].…”

Analysis of the Microheterogeneity of the IgA1 Hinge Glycopeptide Having Multiple O-Linked Oligosaccharides by Capillary Electrophoresis

“…Such microheterogeneity of a glycoprotein is a well-known phenomenon (26). However, the importance of the structure of the hinge portion of IgA1 should not be ignored because of the relationship with IgA nephropathy and because incompleteness of a sugar chain on the hinge portion would be related to the stability of the IgA1 molecule and the self-aggregation of IgA1 (5)(6)(7)(8)(17)(18)(19)(20).…”

Establishment of a Lens Epithelial Cell Line from a Canine Mature Cataract

“…To detect the SV40 T antigen, an antibody against SV40 T antigen, obtained from Bethyl Laboratories (Montgomery, TX, USA) was used. In cytoimmunochemistry analysis was performed basically as described elsewhere [5] using the same anti-aB-crystallin peptide sera. LECs from passage 30 were grown on a chamber slide until a monolayer had formed for immunocytochemical analysis.…”