Gal alpha 4Gal-binding antibodies: specificity and use for the mapping of glycolipids of Burkitt lymphoma and other human tumors.

Abstract

The binding of four different Gal alpha 4Gal-specific antibodies was examined using several natural and synthetic Gal alpha 4Gal-containing glycolipids on thin-layer chromatograms. One of the antibodies, MC2102, bound much better to galabiosylceramide (Gal alpha 4Gal beta Cer) than to the elongated structure globotriaosylceramide (Gal alpha 4Gal beta-4Glc beta Cer, CD77). Two antibodies, 38.13 and Pk002, bound best to globotriaosylceramide but cross-reacted with the P1 antigen (Gal alpha 4Gal beta 3GlcNAc beta 3Gal beta 4Glc beta Cer). 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 Gal alpha 4Gal placed internally in the carbohydrate chains. The synthetic Gal alpha 4Gal beta-bissulfone (3-hexadecylsulfonyl-2-hexadecylsulfonylmethylprop-1-yl) was bound by MC2102, Pk002, and 38.13 with a strength comparable to Gal alpha 4Gal beta Cer. A large number of glycolipids lacking terminal Gal alpha 4Gal 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 Gal alpha 4Gal beta-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 Gal alpha 4Gal beta Cer.