Serum levels of galactose-deficient IgA in children with IgA nephropathy and Henoch-Schönlein purpura
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IgA nephropathy and Henoch-Schönlein purpura nephritis (HSPN) are related diseases characterized by deposits of IgA1-containing immune complexes in the renal mesangium. Adult patients with IgA nephropathy have aberrantly glycosylated IgA1 (galactose-deficient O-linked glycans) in the circulation and renal deposits. However, IgA1 glycosylation has not been studied in pediatric patients with IgA nephropathy. Using our quantitative lectin enzyme-linked immunosorbent assay (ELISA) test, we measured serum levels of galactose-deficient IgA1 of children with IgA nephropathy and HSPN and controls. Children with IgA nephropathy and HSPN had serum levels higher than those of healthy children or renal-disease controls with C1q nephropathy. Furthermore, lectin ELISA identified patients with HSPN whose clinical course mimicked that of IgA nephropathy. In summary, pediatric patients with IgA nephropathy and HSPN have an aberrancy in the glycosylation in IgA1 O-linked glycans that is similar to that in adults with IgA nephropathy.
KeywordsIgA nephropathy Henoch-Schönlein purpura Aberrant glycosylation IgA1 Lectin ELISA
This work was supported by National Institutes of Health grants DK57750, DK61525, DK71802, DK78244, and DK64400, by grants to the General Clinical Research Centers of the University of Tennessee Health Sciences Center M01, RR00211, and the University of Alabama at Birmingham M01, RR00032, and by a generous gift to the University of Tennessee Pediatric Nephrology Research Support Fund by Anna and Donald Waite. The authors express their appreciation to Dr. Kimberly Fisher and Sandra Grimes (University of Tennessee) for collecting serum samples and clinical data and to Rose Kulhavy (University of Alabama at Birmingham) for providing the IgA1 myeloma protein. The authors appreciate the technical assistance of Rhubell Brown, Stacy Hall, Candace Kirksey, and Claretha Nichols in the processing of the serum samples.
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