Humanized
monoclonal antibody HMMC-1 established by immunizing transchromosomal mice with a human uterine
endometrial cancer cell line has been found to react with the
H-antigen carried on core l O-
glycans through cotransfection of
glycosyltransferases for O-
glycans and inhibition of antibody-binding with synthetic
oligosaccharides. However, direct binding analysis of an antibody against
glycosphingolipids from human erythrocytes with different ABO
blood groups revealed that it was able to bind selectively with polar
glycolipids in
blood group O, but not
blood group A, B and AB erythrocytes. Unexpectedly, typical monofucosylated H-
glycolipids, IV2Fucα-nLc4Cer and VI2Fucα-nLc6Cer, which are the precursors for A and B-
glycolipids, and were present not only in
blood group O, but also A, B and AB-erythrocytes, were not the
antigens for the HMMC-1 antibody. The
antigen comprised less than 0.001% of the total
glycolipids in
blood group O-erythrocytes, and was purified by conventional
silica gel column chromatography. Structural determination by permethylation, GC-MS, and ESI-TOFMS demonstrated that the structure was a novel
glycolipid with a difucosylated
H-antigen, Fucα1-2Galβ1-4GlcNAcβ1-3Gal(2-1αFuc)β1-4GlcNAcβ1-3Galβ1-4GlcNAcβ1-3Galβ1-4Glcβ1-1'Cer, VI2,VIII2(Fucα)2-nLc8Cer, whose terminal difucosylated structure was the
epitope of the HMMC-1 antibody. The HMMC-1
glycolipid was detected in five out of 29 tissues from patients suffering from uterine cervical
carcinomas, irrespective of their ABO-
blood groups.