H. Iwase et al., Human serum immunoglobulin G3 subclass bound preferentially to asialo-, agalactoimmunoglobulin A1/Sepharose, BIOC BIOP R, 264(2), 1999, pp. 424-429
Citations number
32
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
As we reported before, exoglycosidase treatment of human serum IgA1 changed
it to a sticky molecule. In order to examine the presence of the specific
binding protein to the sticky IgA1 in human serum, IgA1, asialo-IgA1 (IgA1-
S) and asialo-, agalacto-IgA1 (IgA1-SG)/Sepharose column chromatography of
normal human serum was carried out. Purified hinge glycopeptide (HGP33) pre
pared from IgA1 was used for the preparation of HGP/Sepharose. A portion of
the serum protein was bound to those columns and eluted with the buffer co
ntaining 1.0 M NaCl. About four times the amount of protein was eluted from
the IgA1-SG/Sepharose column than that from IgA1/Sepharose. Most of the el
uted protein was IgG, and the IgG1 and IgG3 subclasses but neither IgG2 nor
IgG4 was dominant. Under the lower salt concentration, a portion of IgG wa
s also bound to the HGP-SG/Sepharose column. The obtained results coincide
well with the previous report of the co-present of IgG1 and IgG3 with depos
ited IgA1 in IgA nephropathy patients (Aucouturier, P., ef al. (1989) Clin.
Immunol. Immunopathol. 51., 338-347), Thus, the results solved the questio
n of why the IgG3 was co-present with deposited IgA1 in IgA nephropathy pat
ients. (C) 1999 Academic Press.