Non‐immunoglobulin serum proteins prevent the binding of IgG from normal rats and from rats with Th2‐mediated autoimmune glomerulonephritis to various autoantigens including glomerular antigens

It is now well established in normal humans and mice that purification of IgG from serum unmasks their autoantibody activity. Mercuric chloride (HgCl2 ) induces in Brown‐Norway (BN) rats a Th2‐dependent polyclonal B cell activation, a huge increase in serum IgE and IgG1 concentrations, the productio...

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Bibliographic Details
Published in:European journal of immunology 1998-01, Vol.28 (1), p.183-192
Main Authors: Druet, Elvira, Praddaude, Françoise, Druet, Philippe, Dietrich, Gilles
Format: Article
Language:English
Subjects:
Animals
Antigen binding
Antigen-Antibody Reactions - drug effects
Autoantibodies
Autoantibodies - blood
Autoantibodies - immunology
Autoantibodies - isolation & purification
Autoantibodies - metabolism
Autoantigens - immunology
Autoantigens - metabolism
Autoimmune Diseases - blood
Autoimmune Diseases - chemically induced
Autoimmune Diseases - immunology
Autoimmunity
Blood Proteins - pharmacology
Culture Media, Serum-Free
Female
Glomerulonephritis - blood
Glomerulonephritis - chemically induced
Glomerulonephritis - immunology
Immunoglobulin E - immunology
Immunoglobulin G - blood
Immunoglobulin G - immunology
Immunoglobulin G - isolation & purification
Immunoglobulin G - metabolism
Immunoglobulin M - immunology
Lymphocyte Activation
Lymphocyte Cooperation
Male
Mercuric Chloride - toxicity
Mice
Rats
Rats, Inbred BN
Rats, Sprague-Dawley
Serum Albumin, Bovine - immunology
Th2 Cells - immunology
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Summary:It is now well established in normal humans and mice that purification of IgG from serum unmasks their autoantibody activity. Mercuric chloride (HgCl2 ) induces in Brown‐Norway (BN) rats a Th2‐dependent polyclonal B cell activation, a huge increase in serum IgE and IgG1 concentrations, the production of numerous autoantibodies and an autoantibody‐mediated glomerulonephritis. In the present study we have compared the IgG autoantibody activity in the serum and in the purified IgG fraction from normal and HgCl2 ‐injected BN rats. IgG autoantibodies were found to be masked in normal serum by non‐immunoglobulin (non‐Ig) serum proteins and, provided these IgG did not encounter normal serum proteins, they could bind to glomerular antigens as assessed by immunofluorescence in a unilateral perfused kidney model. As a consequence of HgCl2 ‐induced polyclonal activation of B cells, IgG autoantibodies were no longer complexed to non‐Ig serum proteins, they were easily detected in the serum and could therefore reach their glomerular target. However, these autoantibodies could still be blocked by normal non‐Ig serum proteins not only in vitro but also in a unilateral perfused kidney model so that their binding to glomerular antigens could be prevented. These findings indicate that the ratio between autoantibody level and the amount of non‐Ig serum proteins may be crucial in autoantibody‐mediated autoimmune diseases.
ISSN:0014-2980
1521-4141
DOI:10.1002/(SICI)1521-4141(199801)28:01<183::AID-IMMU183>3.0.CO;2-O