Volume 54, Issue 3 pp. 914-926
Research Article

Critical comparative analyses of anti–α-actinin and glomerulus-bound antibodies in human and murine lupus nephritis

Manar Kalaaji

Manar Kalaaji

University of Tromsø, Tromso, Norway

Search for more papers by this author
Gunnar Sturfelt

Gunnar Sturfelt

University Hospital of Lund, Lund, Sweden

Search for more papers by this author
Janne Erikke Mjelle

Janne Erikke Mjelle

University of Tromsø, Tromso, Norway

Search for more papers by this author
Hans Nossent

Hans Nossent

University Hospital of Northern Norway, and University of Tromsø, Tromso, Norway

Drs. Nossent and Rekvig have received honoraria for lectures at conferences that were officially sponsored by Pharmacia Diagnostics.

Search for more papers by this author
Ole Petter Rekvig

Corresponding Author

Ole Petter Rekvig

University Hospital of Northern Norway, and University of Tromsø, Tromso, Norway

Drs. Nossent and Rekvig have received honoraria for lectures at conferences that were officially sponsored by Pharmacia Diagnostics.

Department of Biochemistry, Institute of Medical Biology, University of Tromsø, N-9037 Tromso, NorwaySearch for more papers by this author
First published: 28 February 2006
Citations: 83

Abstract

Objective

Although anti–double-stranded DNA (anti-dsDNA) antibodies are important in lupus nephritis, the question regarding which glomerular structures (α-actinin, nucleosomes, or others) are recognized by nephritogenic anti-dsDNA antibodies is still controversial. In this study, we determined which glomerular structures are recognized by monoclonal and in vivo–bound nephritogenic antibodies.

Methods

Western blotting was used to analyze the ability of nephritogenic anti-dsDNA antibodies to recognize glomerular and nucleosomal structures. Sera from patients with lupus nephritis, sera from random antinuclear antibody–positive patients, and paired antibodies from sera and kidney eluates from nephritic (NZB × NZW)F1 mice were analyzed for activity against proteins identified by monoclonal nephritogenic antibodies, and against α-actinin, dsDNA, nucleosomes, histone H1, heparan sulfate, DNase I, and type IV collagen. Immunoelectron microscopy was used to determine the glomerular localization of α-actinin and in vivo–bound autoantibodies in nephritic (NZB × NZW)F1 mouse kidneys.

Results

Anti–α-actinin antibodies were observed in human and murine lupus nephritis sera and in sera from patients without systemic lupus erythematosus and were not detected in kidney eluates from nephritic mice. Antibodies to dsDNA and histone H1 were detected in all eluates. Western blot analyses revealed that nephritogenic anti-dsDNA antibodies recognized a 32-kd band, identified as histone H1. Competitive enzyme-linked immunosorbent assay demonstrated that nephritogenic monoclonal antibodies, and dominant antibodies eluted from nephritic kidneys, cross-reacted with dsDNA and H1. This cross-reactive anti-H1 specificity was largely absent in sera from those mice. Immunoelectron microscopic analysis of nephritic (NZB × NZW)F1 mouse kidneys revealed that antibodies eluted from kidneys, but not anti–α-actinin antibodies, bound to distinct nephritis-associated electron-dense structures linked to glomerular basement membranes.

Conclusion

Cross-reactive anti-dsDNA/anti–histone H1 antibodies, but not anti–α-actinin antibodies, are central among those deposited in nephritic glomeruli.

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.

click me