ABH and Lewis histo-blood group antigens in cancer

Antigens of the ABH and Lewis histo-blood group family can be found on many normal cells, mainly of epithelial type. In carcinomas, altered expression of the various carbohydrate epitopes of this family occur, and are often s trongly associated with either a good or bad prognosis. A review of the ava ilable data on these tumor-associated markers, their biosynthesis and their prognostic value is proposed here. For a long time it has been unclear whe ther their presence could affect the behavior of carcinoma cells. Recent da ta, however, indicate that they play biological roles in the course of tumo r progression. The presence of sialyl-Le(a) or sialyl-Le(x), which are liga nds for selectins, promotes the metastatic process by facilitating interact ion with the endothelium of distant organs. The loss of A and B antigens in creases cellular motility, while the presence of H epitopes increases resis tance to apoptosis by mechanisms that remain to be defined. The Le(y) antig en has procoagulant and angiogenic activities. All these observations are u sed to present a model that may account for the described associations betw een the presence or loss of these markers and the outcome of disease. Final ly, their potential clinical applications as tumor-associated markers or as targets of immunotherapy are reviewed.