The
monoclonal antibody 5-D-4 recognizes heavily sulphated forms of keratan sulphate
epitope. It reacted strongly with the cell surfaces of most thyroid
papillary carcinomas from all the individuals examined, independently of the
blood group of the patients. Cells of follicular variants of
papillary carcinomas were also labelled by 5-D-4. In contrast, no labelling with this antibody was observed in other types of
thyroid neoplasms, or in normal tissues. The reactivity of 5-D-4 with
papillary carcinomas was markedly reduced or abolished by prior digestion with
endo-beta-galactosidase,
keratanase II, or
N-glycosidase F. Although
keratanase digestion had no effect on 5-D-4 labelling, it revealed the binding sites of
Griffonia simplicifolia agglutinin II (GSA-II), which recognizes terminal
N-acetylglucosamine in a limited number of
carcinoma cells from some individuals.
Blood group ABH antigens, which are simultaneously expressed together with keratan sulphate
epitope in
cancer cells, were eliminated by digestion with
endo-beta-galactosidase and
N-glycosidase F, but were resistant to
keratanase and
keratanase II treatment. These results indicate that keratan sulphate
oligosaccharides are
cancer-associated and are probably oncofoetal
antigens, as are the
blood group antigens in human thyroid glands. The results suggests that
poly-N-acetyllactosamine, which is ubiquitously and consistently produced in
papillary carcinomas, is modified in two different ways: sulphation on the 6-position of at least some units of either
galactose or
N-acetylglucosamine or both, and decoration of non-reducing termini with the
blood group antigens. Along with the
endo-beta-galactosidase-GSA-II labelling procedure, labelling with 5-D-4 may be a useful diagnostic means for distinguishing
papillary carcinoma from other types of
thyroid neoplasms.