Original Investigations
Factor H-related protein-5: A novel component of human glomerular immune deposits*,**,*

https://doi.org/10.1053/ajkd.2002.29873Get rights and content

Abstract

Factor H-related protein-5 (FHR-5) is a newly described human plasma protein with structural similarities to human factor H and the four other recently described factor H-related proteins. Unlike the other factor H-related proteins, FHR-5 was initially identified at the protein, rather than complementary DNA, level in studies of glomerular immune deposit composition. To determine the incidence and pattern of detection of FHR-5 in human renal biopsy specimens, a prospective study of 100 consecutive biopsies was performed using anti-FHR-5 monoclonal antibody and indirect immunofluorescence. The pattern of FHR-5 deposition is very similar to that of other complement components, C3 and SC5b-9. It is detected in all complement-containing glomerular immune deposits and has a pattern of extraglomerular deposition similar to that of other complement components. This study shows FHR-5 to be strongly associated with glomerular complement deposition and suggests a role in complement activation or regulation. It may be an important mediator of glomerular disease. © 2002 by the National Kidney Foundation, Inc.

Section snippets

Materials and methods

Methods used in this study, identical to those reported in a previous immunohistological study of human renal biopsy specimens,3 are repeated here in summary form. From 100 consecutive percutaneous renal biopsies performed at St Vincent's Hospital Melbourne (Australia), cases were included if there was sufficient material to achieve adequate light microscopic, immunofluorescence, and electron microscopy assessment.

Light and electron microscopy were performed using conventional laboratory

Renal biopsy diagnoses

Ninety-two of 100 consecutive biopsy specimens contained adequate material for both diagnostic purposes and the special immunohistological studies. The final histopathologic diagnoses for these 92 cases are listed in Table 1.

Distribution of FHR-5 by immunofluorescence

There were three patterns of FHR-5 localization, which were similar to patterns observed with other complement proteins.

Discussion

It has long been known that components of the complement pathways are present in glomerular immune deposits.4 Experimental studies have shown a number of glomerular disease models to be complement dependent,5 and the widespread detection of complement in human glomerulonephritis likely is associated with similar complement-dependent mechanisms. Pathogenic roles suggested for complement in immune glomerular injury range from the phlogistic properties of anaphylotoxins to a variety of nonlytic

References (10)

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Supported in part by the National Health and Medical Research Council of Australia and the Baxter Extramural Grant Programme.

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Address reprint requests to Brendan Murphy, MD, PhD, Director of Nephrology, St Vincent's Hospital, Melbourne, Fitzroy 3065, Victoria, Australia. E-mail: [email protected]

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0272-6386/02/3901-0003$35.00/0

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