H-type 3 blood group antigen (H-type 3)

H-type 3 blood group antigen is a complex carbohydrate structure, specifically Fucα1-2Galβ1-3GalNAcα-Ser/Thr, that functions as a specialized member of the ABO blood group system [1]. Unlike the more common H type 1 and type 2 antigens found on various glycoproteins and glycolipids, H type 3 is primarily an O-linked glycan found on specific proteins in individuals with the A1 and B blood phenotypes [2]. It serves as the biosynthetic precursor for the A type 3 and B type 3 antigens, which are critical for defining certain blood group subgroups [1]. In clinical oncology, H-type 3 is recognized as a tumor-associated carbohydrate antigen (TACA), with altered expression patterns observed in epithelial cancers such as gastric and colorectal carcinomas [3]. This makes the glycan a potential target for diagnostic imaging and the development of targeted immunotherapies, including monoclonal antibodies [5]. Additionally, H-type 3 glycans serve as attachment receptors for several human pathogens, including Noroviruses and Helicobacter pylori, which utilize these structures to facilitate host cell infection [4]. Therapeutic strategies targeting this molecule often involve the use of lectins or antibodies to block pathogen entry or to mediate immune responses against malignant cells [5]. However, the structural similarity between different H-antigen types poses a significant challenge for achieving the high specificity required for therapeutic safety [1]. Citations: [1] Varki A, et al. Essentials of Glycobiology. 3rd edition. (2015-2017). [2] Clausen H, et al. J Biol Chem. 261(30):13807-13 (1986). [3] Hakomori S. Adv Exp Med Biol. 491:369-402 (2001). [4] Marionneau S, et al. Gastroenterology. 122(7):1967-77 (2002). [5] David L, et al. Cancer Res. 53(22):5494-500 (1993).

Other names

H type 3 glycanFucα1-2Galβ1-3GalNAcα-RBlood group H type 3H3 antigen

Binding of specific lectins or monoclonal antibodies to the glycan structure to inhibit pathogen attachment or induce immune-mediated destruction of tumor cells.