T and Tn, General Carcinoma Autoantigens

Abstract

Primary and metastatic carcinomas are epithelial in origin and comprise by far the largest group of malignant tumors in humans. In most of these tumors, T and Tn antigens, whose epitopes have been synthesized, are uncovered and immunoreactive. In all other tissues T and Tn antigens are masked and not accessible to the immune system; they are generally precursors in normal complex carbohydrate chains. Thus, carcinomas have antigens recognized as foreign by the patients' immune system. The expression of T and Tn antigens has pathogenic and clinical consequences, and the antigens themselves are powerful histological markers in carcinoma diagnosis and frequently in prognosis. Most patients distinguish their carcinoma from all other cells, as shown by strong autoimmune responses to T antigen. These responses are readily measured by assays, and they allow detection of carcinomas with greater sensitivity and specificity frequently earlier than previously possible. Moreover, the extent of T and Tn expression often correlates with carcinoma differentiation; on a molecular level, clustered T- and Tn-active structures on carcinoma cell surfaces may be involved in invasion.

C2GnT-M is downregulated in colorectal cancer and its re-expression causes growth inhibition of colon cancer cells

“…Several tumor-associated antigens have been identified on mucins (Springer, 1984;Cao et al, 1995;Fukuda, 1996;Baldus et al, 2000;Schneider et al, 2001;Hakomori, 2002). Mucin-type glycoproteins are heavily glycosylated and are mainly decorated with complex O-glycans.…”

“…T antigen (core 1 structure) and its related carbohydrate antigens, such as Tn, T, and their sialylated variants, are oncofetal carbohydrate antigens (Springer, 1984;Cao et al, 1995;Fukuda, 1996;Brockhausen, 1998Brockhausen, , 1999Baldus et al, 2000;Schneider et al, 2001;Hakomori, 2002). Changes in the expression of T antigen-related carbohydrates on cell surfaces have been observed in a variety of cancers (Hanisch and Baldus, 1997).…”

Combined evaluation of preoperative serum sialyl-Tn antigen and carcinoembryonic antigen levels is prognostic for gastric cancer patients

“…Changes in surface membrane glycoproteins are common phenomena in cancer cells (Springer, 1984). Itzkowitz et al (1989Itzkowitz et al ( , 1990 reported that the rate of expression of STN is low in normal colon mucosa, and that expression of STN is an independent prognostic factor for colon cancer patients.…”

Obtención y purificación de IgY dirigidas contra la lectina de Salvia bogotensis.

“…La exposición del antígeno Tn en eritrocitos ocasiona el síndrome Tn, o síndrome de poliaglutinabilidad, que es un trastorno caracterizado por la presencia de residuos de N-acetilgalactosamina (GalNAc) en la superficie de la célula roja que, normalmente, se encuentran enmascarados y unidos a Ser/Thr en las sialoglicoproteínas de membrana (17,18). Los antígenos T y Tn también se han encontrado asociados a carcinomas, expuestos en la membrana externa de células tumorales comunes y en metástasis (19,20); la proporción relativa de estos antígenos en las células está estrechamente relacionada con la agresividad con la que evoluciona el tejido canceroso (20).…”