Galα4Gal-binding antibodies: Specificity and use for the mapping of glycolipids of Burkitt lymphoma and other human tumors

Abstract

The binding of four different Galα4Gal-specific antibodies was examined using several natural and synthetic Galα4Gal-containing glycolipids on thin-layer chromatograms. One of the antibodies, MC2102, bound much better to galabiosylceramide (Galαw4GalβCer) than to the elongated structure globotriaosylceramide (Galα4Galβ4Galβ4GlcβCer, CD77). Two antibodies, 38.13 and Pk002, bound best to globotriaosylceramide but cross-reacted with the P1 antigen (Galα4Galβ3GlcNAcβ3Galβ4GlcβCer). The fourth antibody tested, P001, reacted most strongly with the P1 antigen but also to some extent with globotriaosylceramide. None of the antibodies bound to glycolipids with Galα4Gal placed internally in the carbohydrate chains. The synthetic Galα4Galβ-bissulfone (3-hexadecylsulfonyl-2-hexadecylsulfonylmethylprop-1-yl) was bound by MC2102, Pk002, and 38.13 with a strength comparable to Galα4GalβCer. A large number of glycolipids lacking terminal Galα4Gal were also tested, but none of the antibodies bound to any of these structures. The specificity of the studied antibodies was used to investigate the presence of Galα4Galβ-containing glycolipids in several human and animal tissues and cells and in an experimental Burkitt lymphoma cell line grown in nude mice. Glycolipids were also isolated from a series of human tumors and several of them were, by antibody binding, found to contain Galα4GalβCer.