Reference : Evidence that the interaction between circulating IgA and fibronectin is a normal proces...
Scientific journals : Article
Human health sciences : Rheumatology
http://hdl.handle.net/2268/94598
Evidence that the interaction between circulating IgA and fibronectin is a normal process enhanced in primary IgA nephropathy
English
Davin, J. C. [ > > ]
Li Vecchi, M. [ > > ]
Nagy, J. [ > > ]
Foidart, J. M. [ > > ]
Foidart, J. B. [ > > ]
Barbagallo Sangiorgi, G. [ > > ]
Malaise, Michel mailto [Université de Liège - ULg > Département des sciences cliniques > Rhumatologie >]
Mahieu, P. [ > > ]
1991
Journal of Clinical Immunology
Kluwer Academic/Plenum Publishers
11
2
78-94
International
0271-9142
New York
NY
[en] Antigen-Antibody Complex ; Fibronectins ; Immunoglobulin A ; Edetic Acid ; Calcium
[en] A solid-phase ELISA was set up to measure the direct binding capacity (BC) of
different, commercially available, purified human IgA preparations to plates
coated with human fibronectin (FN). It was found that secretory, polymeric, and,
to a much lesser extent, monomeric IgA exhibited elevated FN-BC as compared to
their BC to plates coated with bovine serum albumin. This binding was specific
since not observed with human IgG or IgM antibodies. In addition, we noted that
this interaction was dose dependent, Ca2+ dependent, saturable, and not covalent,
was inhibited by soluble FN, but not by a prior incubation of FN-coated plates
with anti-human fibronectin antibodies, and appeared to involve on the dimeric FN
other structures than its heparin-binding, collagen-binding, or C1q-binding
domains. Similar experiments conducted with normal plasma indicated that plasma
IgA, but not plasma IgG or IgM, was also capable of significant binding to
FN-coated plates. In contrast, serum IgA did not significantly bind to those
plates under otherwise identical experimental conditions. Thus, the coagulation
process induces a strong decrease in the FN-BC of circulating IgA, which implies
the necessity of using plasma rather than serum to study such interactions. The
apparent molecular weight of plasma IgA interacting with FN-coated plates ranged
between 450 and 900 kd, and its major binding characteristics were quite similar
to those observed with purified polymeric IgA. The FN-BC of plasma IgA was then
measured by the same ELISA in 30 patients with primary IgA nephropathy (IgAN) and
in 23 healthy controls. The mean FN-BC of plasma IgA was significantly higher in
patients than in normal controls. This enhancement was due mainly to the
augmentation in the concentration of circulating "macromolecular" IgA and was
significantly correlated with the plasma levels of IgA-FN complexes. However, the
pathogenetic role of these findings was probably not determinant since similar
observations were made in alcoholic liver cirrhosis without urinary abnormalities
and since the FN-BC of plasma IgA or the plasma levels of IgA-FN complexes were
not correlated with the various biological parameters of evolutivity of primary
IgAN. In conclusion, these studies suggest that the ability of polymeric IgA to
directly bind to FN is involved in the formation of circulating IgA-FN complexes
and that this normal binding process, although enhanced in IgAN, is probably not
responsible for kidney injury, at least in the patients studied.
Researchers ; Professionals
http://hdl.handle.net/2268/94598

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