title: Anti-idiotypic antibody mimicking a T-antigen-specific lectin inhibits human epithelial tumor cell proliferation.
abstract: Cancer-associated mucins show frequent alterations of oligosaccharide chain profile. Terminal structures may be deleted, thereby exposing normally 'cryptic' structures such as Tn (GalNAcα-O-Ser/Thr) and T antigen (Galβ1-3GalNAcα-O-Ser/Thr). Overexpression of these commonly hidden glycoforms, and reduced level of naturally occurring anti-T or anti-Tn antibodies, is associated with epithelial tumor progression and aggressiveness. The lectin from the common edible mushroom Agaricus bisporus (ABL) shows high affinity binding to T antigen, and reversible noncytotoxic inhibitory effect on epithelial tumor cell proliferation. The aim of this study was to induce immune response with tumor-associated glycan specificity and biological activity similar to those of ABL. An anti-idiotypic (Id) antibody strategy was developed using ABL as first template. ABL was purified by affinity chromatography and assayed as immunogen in rabbit. Rabbit IgG was purified from anti-ABL serum using a protein G column, and specific anti-ABL IgG was obtained by affinity chromatography using immobilized ABL. Affinity-purified anti-ABL IgG contained an antibody fraction that recognizes the carbohydrate-binding site of ABL. This IgG was used as immunogen in mouse to yield anti-Id antibody recognizing tumor-associated glycans such as Tn and T antigen. Competitive assays showed that α-anomeric GalNAc is the main binding subsite of anti-Id antibody in glycan recognition. Anti-Id antibody bound human epithelial tumor cells, as shown by cell enzyme-linked immunosorbent assay and immunofluorescence. Anti-Id antibody raised by immunization with affinity-purified anti-ABL IgG had antiproliferative effect on human epithelial tumor cells through apoptosis induction similar to that of ABL. The anti-Id immune response developed here has potential application in cancer therapy.
authors.affiliation: Facultad de Ciencias Químicas, Departamento de Química Biológica, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC, UNC-CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina.
authors.forename: Victor G
authors.initials: VG
authors.lastname: Sendra
authors.forename: Natacha
authors.initials: N
authors.lastname: Zlocowski
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Nores
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Irazoqui
mesh_terms: D000364:Agaricus / Q000276:immunology; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000494:pharmacology*; D000957:Antigens, Viral, Tumor / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology; D002277:Carcinoma / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology; D048708:Cell Growth Processes / Q000187:drug effects / Q000276:immunology; D002478:Cells, Cultured; D002846:Chromatography, Affinity; D000939:Epitopes / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D007114:Immunization; D007074:Immunoglobulin G / Q000276:immunology; D037102:Lectins / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism; D051379:Mice; D011485:Protein Binding / Q000276:immunology; D011817:Rabbits
chemical_list: C041433:Agaricus lectins; D000888:Antibodies, Anti-Idiotypic; D000957:Antigens, Viral, Tumor; D000939:Epitopes; D007074:Immunoglobulin G; D037102:Lectins