Rapid production of a panel of blood group A-active oligosaccharides using chemically synthesized di- and tri-saccharide primers and an easily prepared porcine (1-->3)-alpha-N-acetyl-D-galactosaminyltransferase

Synthesis and NMR studies on the ABO histo-blood group antigens: synthesis of type III and IV structures and NMR characterization of type I-VI antigens

The ABO histo-blood group antigens are best known for their important roles in solid organ and bone marrow transplantation as well as transfusion medicine. Here we report the synthesis of the ABO type III and IV antigens with a 7-octen-1-yl aglycone. Also described is an NMR study of the ABO type I to VI antigens, which were carried out to probe differences in overall conformation of the molecules. These NMR investigations showed very little difference in the (1)H chemical shifts, as well as (1)H-(1)H coupling constants, across all compounds, suggesting that these ABO subtypes adopt nearly identical conformations in solution.

Synthesis of ABO Histo-Blood Group Type V and VI Antigens

The ABO histo-blood group antigens have long been of interest to chemists, biochemists, and evolutionary biologists. However, to date, a complete synthesis of all ABO histo-blood group antigens has not been conducted, despite the potential for such a panel to provide a more detailed understanding of the biological roles of these glycan motifs. Here we report the chemical synthesis of the A, B, and H type V and VI antigens in multi-milligramme quantities as part of an overall goal to prepare all 18 A, B, and H antigens. The A and B type V and VI antigens were prepared with a 7-octen-1-yl linker, to enable future conjugation to a protein or solid support. The H type V and VI antigens were prepared as the octyl glycoside, to facilitate detailed enzyme kinetics studies.

Monoclonal antibody recognizing a determinant on type 2 chain blood group A and B oligosaccharides detects oncodevelopmental changes in azoxymethane-induced rat colon tumors and human colon cancer cell lines

Altered expression of ABH blood group substances is a common feature of human colorectal carcinoma, yet it remains unclear how these structural changes influence the biological properties of tumor cells. Azoxymethane-induced rat colon tumors display many features of the human disease, thereby providing a potentially useful model to study the role of blood group substances in colon cancer progression. We have prepared monoclonal antibodies to a microsomal fraction isolated from an azoxymethane-induced rat colon tumor and selected an antibody that detects cancer-associated changes. Monoclonal antibody (mAb) 3A7 recognizes a determinant on type 2 chain blood group A (GalNAc alpha 1-3[Fuc alpha 1-2]Gal beta 1-4GlcNAc-R) and B (Gal alpha 1-3[Fuc alpha 1-2]Gal beta 1-4GlcNAc-R) oligosaccharides. Expression of the epitope detected by this antibody was developmentally regulated in rat colon, with maximal expression from day 4-21 after birth. Immunohistochemical staining and Western blotting analyses of azoxymethane-induced colon tumors revealed increased expression of the epitope in all of the 21 colonic tumors examined, including preneoplastic glands within transitional mucosa. Conventional and signet-ring adenocarcinomas that had invaded through the muscularis propria (Duke's B2) consistently showed the most intense staining with mAb 3A7, including regions depicting angioinvasion. Some of the lymph node metastases (Duke's C2) stained poorly with the antibody. The epitope was also expressed in blood group A positive human colon carcinoma cell lines, including HT29 and SW480 but not by SW620, a cell line derived from a lymph node metastasis isolated in vivo from the SW480 primary tumor, or in the blood group B cell line SW1417. The glycoproteins detected by mAb 3A7 in rat colon tumors and HT29 cells ranged in size between 50 and 200 kd, including a major species of 140 kd. Affinity chromatography of detergent lysates of normal rat colon on the blood group A specific lectin Dolichos biflorus (DBA)-agarose resulted in nearly quantitative binding of glycoprotein species detected by the antibody. By contrast, immunoreactive glycoproteins from rat colon tumors or HT29 cells bound poorly to DBA-agarose but were retained by another blood group A-binding lectin, Helix-pomatia (HPA)-agarose. These results indicate that colon carcinogenesis results in quantitative as well as qualitative changes in oligosaccharides detected by mAb 3A7 and suggest that the combined use of mAb 3A7 and blood group A-specific lectins may provide a useful tool for early detection of colon cancer.