Clinical significance of IgG deposition in the glomerular mesangial area in patients with IgA nephropathy

• Published in: Clinical and experimental nephrology Vol. 17; no. 1; pp. 73 - 82
• Main Authors: Wada, Yukihiro, Ogata, Hiroaki, Takeshige, Yui, Takeshima, Akiko, Yoshida, Noriyo, Yamamoto, Masahiro, Ito, Hidetoshi, Kinugasa, Eriko
• Format: Journal Article
• Language: English
• Published: Japan Springer Japan 01.02.2013; Springer Nature B.V
• Subjects: Adolescent; Adult; Biopsy; Female; Fluorescent Antibody Technique; Glomerular Mesangium - immunology; Glomerular Mesangium - pathology; Glomerulonephritis, IGA - immunology; Glomerulonephritis, IGA - pathology; Glomerulonephritis, IGA - therapy; Humans; IgA nephropathy; IgA-IgG nephropathy; IgG deposition; Immunoglobulin A - analysis; Immunoglobulin G - analysis; Kaplan-Meier Estimate; Male; Medicine; Medicine & Public Health; Middle Aged; Multivariate Analysis; Nephrology; Original; Original Article; Predictive Value of Tests; Proportional Hazards Models; Proteinuria - immunology; Proteinuria - pathology; Reagent Strips; Remission Induction; Retrospective Studies; Risk Factors; Severity of Illness Index; Treatment Outcome; Urinalysis - instrumentation; Urine - cytology; Urology; Young Adult; IgA-IgG nephropathy; IgG deposition; IgA nephropathy
• ISSN: 1342-1751; 1437-7799; 1437-7799
• DOI: 10.1007/s10157-012-0660-0

Background Immunoglobulin (Ig) A nephropathy (IgAN) is characterized by mesangial deposits of IgA1 and C3, often with co-deposits of IgG. We attempted to clarify the clinical significance of mesangial IgG deposition in patients with IgAN. Methods We retrospectively reviewed 57 patients who were diagnosed with IgAN on the basis of pathological examination of renal biopsy specimens obtained between October 2006 and December 2010. Subjects were divided into two groups: IgA+IgG deposition (IgA-IgG) group ( n  = 29) and IgA deposition alone (IgA) group ( n  = 28). The study outcome was complete remission (CR), defined as negative proteinuria by dipstick urinalysis and urinary erythrocytes of less than 1–4/high-power field. Results Proteinuria was greater in the IgA-IgG group than the IgA group (1.1 ± 0.8 vs. 0.7 ± 0.6 g/day, Mann–Whitney U test, P  = 0.042). Capillary wall IgA deposits were noted more frequently in the IgA-IgG group than the IgA group (59 vs. 11 %, Fisher’s exact test, P  = 0.014). During the median follow-up period of 33.3 months (range 6–55 months) in the 57 patients, we observed CR in 24 cases (42.1 %). After the start of treatment, urinary abnormalities disappeared earlier in the IgA group than in the IgA-IgG group (log rank test, P  = 0.012). Cox’s regression model showed that IgG deposition reduced the hazard ratio for CR (hazard ratio 0.35; 95 % confidence interval 0.14–0.82, P  = 0.014). Therefore, IgG deposition is a risk factor for persistent urinary abnormalities. Conclusion Mesangial IgG deposition is associated with more severe clinical features in patients with IgAN.