Isolation and Characterization of Thomsen-Friedenreich-Specific Antibodies from Human Serum

Abstract

The Thomsen-Friedenreich (TF) disaccharide, galactose (Gal)β1–3GalNAcα-, is a blood group-related oncofetal antigen with remarkable tumor specificity. Postpartum, carbohydrate structures on the cell walls of the gastrointestinal flora evoke natural antibodies of presumed TF specificity. These antibodies may provide an early barrier against TF-carrying tumor cells. Their possible role, however, has been difficult to assess, since so far only a multivalent immunosorbent, asialoglycophorin (aGP), has been employed for their preparation, and therefore their fine specificities have been only insufficiently defined. We have used a novel immunosorbent consisting of synthetic TFα disaccharides (Galβ1–3GalNAcα-) coupled to polyacrylamide (PAA), which itself was covalently bound to cross-linked sepharose. For specificity analyses, aGP and a panel of PAA-conjugated mono- and oligosaccharides were employed. Binding to the PAA moiety was excluded. The affinity-purified anti-TFα antibodies were of the IgM (≧0.5 mg/100 ml of serum) and IgG (approximately 0.05 mg/100 ml of serum) classes. They did partially cross-react with TFβ, although we detected a second group of anti-TFβ antibodies (both IgM and IgG) which did not cross-react with TFα. The affinity-purified TFα antibodies showed only marginal cross-reactivity with the related antigens lactose, Gal, Tn or the Forssman antigen. Besides TF-specific antibodies, we found antibodies to the carbohydrate antigens Tn, Forssman and β-D-Gal as well as to noncarbohydrate epitopes of glycophorin in human serum.