Chemical synthesis of alpha-L-fucopyranosylceramide and its analogues and preparation of antibodies directed to this glycolipid.

Abstract

A novel glycolipid, alpha-L-fucopyranosylceramide, was previously isolated and characterized from metastatic human adenocarcinoma [Watanabe, K., Matsubara, T., & Hakomori, S. (1976) J. Biol. Chem. 251, 2385-2387]. For further investigation of the pathobiological significance of this glycolipid with its specific antibodies, the antigen glycolipid alpha-L-fucopyranosylceramide was chemically synthesized by Königs-Knorr-type condensation of 2,3,4-tri-O-benzyl-alpha-L-fucopyranosyl bromide and a ceramide, followed by removal of benzyl groups by catalytic hydrogenation. alpha-L-Fucopyranosyl-N-palmitoylethanolamine and 2,3,4-tri-O-benzyl-alpha-L-fucopyranosylsphingosine were also synthesized. The antibodies prepared against a synthetic alpha-L-fucopyranosyl-ceramide included in liposome reacted very well with the synthetic as well as the natural alpha-L-fucopyranosylceramide isolated from human adenocarcinoma, but the kinetics of the complement-dependent liposome lysis and the complement fixation pattern with the synthetic fucosylceramide were significantly different from those with the natural fucosylceramide. The natural fucosylceramide showed a much weaker immunogenicity than the synthetic fucosylceramide. The remarkable difference in liposome lysis, complement fixation, and immunogenicity between the synthetic and the natural fucosylceramide must be due to the difference in ceramide structures. The results indicate that the strength of antigenicity and immunogenicity of glycolipids may greatly depend on ceramide structure, whereas the specificity is solely determined by the sugar moiety. The anti-alpha-L-fucosylceramide antibodies display cross-reactivity with galactosylceramide, ceramide, and liposome alone that was eliminated by absorption with galactosylceramide liposomes.