Immunoglobulin A: Interaction with Complement, Phagocytic Cells and Endothelial Cells

Wm, Bogers; Stad, Robert; La, van Es; Mr, Daha

doi:10.1159/000463206

Cited by 31 publications

(18 citation statements)

References 31 publications

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“…Several studies have demonstrated that activation of the complement system augments the inflammatory cascade and potentiates tissue injury in IgAN (13). Roos et al (14) showed that those patients with IgAN with glomerular deposition of mannose-binding lectin (MBL) had more severe histologic damage and more proteinuria.…”

Section: Introductionmentioning

confidence: 99%

Association of C4d Deposition with Clinical Outcomes in IgA Nephropathy

Espinosa¹,

Ortega²,

Sánchez³

et al. 2014

Clinical Journal of the American Society of Nephrology

179

162

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Background and objectives Several studies have suggested that activation of the complement system is a contributing pathogenic mechanism in IgA nephropathy (IgAN). C4d staining is an inexpensive and easy-toperform method for the analysis of renal biopsies. This study aimed to assess the clinical and prognostic implications of C4d staining in IgAN.Design, setting, participants, & measurements This retrospective cohort study included 283 patients with IgAN in 11 hospitals in Spain who underwent a renal biopsy between 1979 and 2010. The primary predictor was mesangial C4d staining. Secondary predictors included demographic, clinical, and laboratory characteristics, and Oxford pathologic classification criteria. The primary end point was the cumulative percentage of patients who developed ESRD, defined as onset of chronic dialysis or renal transplantation. C4d was analyzed by immunohistochemical staining using a polyclonal antibody. Kaplan-Meier and Cox proportional hazards analyses were performed to evaluate the effect of C4d staining on renal survival.Results There were 109 patients (38.5%) and 174 patients (61.5%) who were classified as C4d positive and C4d negative, respectively. Renal survival at 20 years was 28% in C4d-positive patients versus 85% in C4d-negative patients (P,0.001). Independent risk factors associated with ESRD were as follows: proteinuria (hazard ratio [HR] per every 1 g/d increase. 1.16; 95% confidence interval [95% CI], 1.03 to 1.31; P=0.01), eGFR (HR per every 1 ml/min per 1.73 m 2 increase, 0.96; 95% CI, 0.94 to 0.97; P,0.001), T2 Oxford classification (tubular atrophy/ interstitial fibrosis, .50%; HR, 4.42; 95% CI, 1.40 to 13.88; P=0.01), and C4d-positive staining (HR, 2.45; 95% CI, 1.30 to 4.64; P=0.01).Conclusions C4d-positive staining is an independent risk factor for the development of ESRD in IgAN. This finding is consistent with the possibility that complement activation is involved in the pathogenesis of this disease.

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Section: Introductionmentioning

confidence: 99%

Association of C4d Deposition with Clinical Outcomes in IgA Nephropathy

Espinosa¹,

Ortega²,

Sánchez³

et al. 2014

Clinical Journal of the American Society of Nephrology

179

162

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“…Complement activation by IgA has been previously shown to involve the alternative, but not the classical complement pathway (16,17). No data are available concerning the possible involvement of the lectin pathway.…”

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confidence: 99%

Human IgA Activates the Complement System Via the Mannan-Binding Lectin Pathway

Roos

et al. 2001

The Journal of Immunology

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387

286

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The recently identified lectin pathway of the complement system, initiated by binding of mannan-binding lectin (MBL) to its ligands, is a key component of innate immunity. MBL-deficient individuals show an increased susceptibility for infections, especially of the mucosal system. We examined whether IgA, an important mediator of mucosal immunity, activates the complement system via the lectin pathway. Our results indicate a dose-dependent binding of MBL to polymeric, but not monomeric IgA coated in microtiter plates. This interaction involves the carbohydrate recognition domain of MBL, because it was calcium dependent and inhibited by mannose and by mAb against this domain of MBL. Binding of MBL to IgA induces complement activation, as demonstrated by a dose-dependent deposition of C4 and C3 upon addition of a complement source. The MBL concentrations required for IgA-induced C4 and C3 activation are well below the normal MBL plasma concentrations. In line with these experiments, serum from individuals having mutations in the MBL gene showed significantly less activation of C4 by IgA and mannan than serum from wild-type individuals. We conclude that MBL binding to IgA results in complement activation, which is proposed to lead to a synergistic action of MBL and IgA in antimicrobial defense. Furthermore, our results may explain glomerular complement deposition in IgA nephropathy.

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“…IgA does not have a C lq bhrdhig site, and therefore fads to fix complement by the classical pathway, but it now seems established that it can activate the alternative pathway in some circumstances , Bogers 1991, Valhn 1991. N-glycosylation of IgA has been shown to be important in C3 binding and production o f terminal complement components in a study employing IgA2 produced in the presence o f tunicamycin, which blocks the Asn-glycosylation pathway (Zhang 1994).…”

Section: 32mentioning

confidence: 99%