Biochemical studies have revealed that some normal cells express the LeX
trisaccharide Gal beta 1----4(Fuc alpha 1----3)GlcNAc either on short-chain
fucolipids or as a single immunodeterminant on
glycolipid oligosaccharide side chains.
Cancer cells, including those from colonic
adenocarcinomas, express this
antigen on longer type 2
blood group side chains as difucosylated or trifucosylated
fucolipids. Moreover, sialylated forms of difucosylated LeX also accumulate in
colon cancer but not in normal colonic mucosa. In the present study, six
monoclonal antibodies which selectively recognize the various LeX-related
antigens were used for immunohistochemical examination of these
antigens in serial sections of human colonic tissue. All of these
antigens were oncodevelopmental in human colon.
Monoclonal antibodies anti-SSEA-1 and AH8-183, directed against short-chain, monofucosylated LeX, were unable to discriminate well between normal and malignant colonic tissue. However, the other four
antibodies were much better at distinguishing
cancer from normal tissue. FH6 was the most specific in that no normal tissues bound this antibody. However, FH6 failed to
stain poorly differentiated
cancers and some
colloid-type
carcinomas. FH4, which was also highly specific, stained almost all
cancers, regardless of the degree of differentiation. FH4 primarily stained
cancer cell cytoplasm, whereas the sialylated
antigen defined by FH6 predominantly stained cell membranes. Differences were noted between the expression of LeX-related
antigens in autopsied normal mucosa compared to mucosa of benign
colonic diseases.
Monoclonal antibodies recognizing long-chain polyfucosylated and sialylated LeX-related
antigens appear to be useful tools for detection of
colon cancer.