Markers blood group antigens

TABLE 23-ii Blood Group Antigen-Related Gancet Markers ... 

Carbohydrate-related tumor markers either are (1) antigens on the tumor cell surface or (2) secreted by the tumor cells. Monoclonal antibodies have been developed against these antigens. These markers have been found to be clinically useful as tumor markers and tend to be more specific than naturally secreted markers, such as enzymes and hormones. Biochemically, they are high molecular weight mucins (Table 23-10) or blood group antigens (Table 23-11). 

K.D. Lloyd, Blood group antigens as markers for normal and abnormal differentiation and malignant change in human tissues. Am. J. Clin. Pathol., 87 (1987) 129-139. 

The agglutination of incompatible red blood cells, which indicates that the body s immune system has recognized the presence of foreign cells in the body and has formed antibodies against them, results from the presence of polysaccharide markers on the surface of the cells. Types A, B, and 0 red blood cells each have characteristic markers, called antigenic determinants, type AB cells have both type A and type B markers. The structures of all three blood-group determinants are shown in Figure 25.15. 

The human blood groups offer another example of how carbohydrates, in the form of glycohpids and glycoproteins, act as biochemical markers. The A, B, and O blood types are determined, respectively, by the A, B, and H determinants on the blood cell surface. (The odd naming of the type O determinant came about for complicated historical reasons.) Type AB blood cells have both A and B determinants. These determinants are the carbohydrate portions of the A, B, and H antigens. 

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