Agaricus bisporus lectin binds mainly O-glycans but also N-glycans of human IgA subclasses.
The primary interaction between purified Agaricus bisporus lectin (ABL) and human IgA subclasses was studied by ABL-affinity chromatography, dot blot assay and competitive enzyme-lectin assay, considering that ABL could be an alternative tool for detection of IgA1 O-glycans. Both secretory IgA subclasses bound to ABL-Sepharose and the IgA2 subclass (which contains only N-glycans) was recovered with a high degree of purity when NH4OH was used as eluent. ABL-Ig interaction was also observed by dot blot assays using ABL-peroxidase against monoclonal IgA1 k Pan, IgA2m(1)k Gir, IgA2m(2)k Bel, secretory IgA2 and normal IgG (also contains only N-glycans). When these immunoglobulins were enzymatically treated with peptide N-glycosidase F (N-glycan hydrolysis), the ABL-IgA2 and -IgG interaction did not occur while IgA1 maintained a high degree of interaction with ABL. Also, the ABL-IgA interaction was observed by competitive enzyme-lectin assay, and when IgA1 subclass was treated with endo-alpha-N-acetylgalactosaminidase for O-glycans hydrolysis, the reactivity with ABL was very low. We conclude that the complementary use of ABL and peptide N-glycosidase F could be a useful tool to assess the O-glycosylation state of human IgA1 subclass, which is of relevant importance in the effector functions of immunoglobulins.
Irazoqui
F J
FJ
Departamento de Bioquímica Clíníca, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
Zalazar
F E
FE
Nores
G A
GA
Vides
M A
MA
D002846:Chromatography, Affinity; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D005779:Immunodiffusion; D007070:Immunoglobulin A / Q000737:chemistry* / Q000145:classification / Q000302:isolation & purification; D007071:Immunoglobulin A, Secretory / Q000737:chemistry* / Q000302:isolation & purification; D037102:Lectins; D008895:Milk, Human / Q000276:immunology; D011134:Polysaccharides / Q000032:analysis*
C041433:Agaricus lectins; D007070:Immunoglobulin A; D007071:Immunoglobulin A, Secretory; D037102:Lectins; D011134:Polysaccharides