Blood group antigens in normal and neoplastic urothelium.
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Overview
abstract
The ABO and Lewis blood group antigens are cell surface carbohydrate determinants formed by the sequential addition of saccharides to precursor backbone structures of membrane lipids and proteins. Suppression of normally active glycosyltransferases results in the absence of antigens that are normally expressed. ABH antigen deletion in malignant and premalignant urothelium has been extensively evaluated; it appears to correlate with significantly higher rates of tumor recurrence and disease progression. However, we have recently shown that the ABH blood group system is differentially expressed in the normal urothelium of secretors in contrast to nonsecretor individuals. The normal urothelium of nonsecretors does not express A, B or H determinants; therefore, deletion of ABH antigens can only be ascertained in secretor individuals. Although nonsecretors only comprise 22-24% of the population, this observation mandates a reevaluation of earlier studies. Deletion of A, B or H antigens is noted in carcinoma in situ (CIS), and in invasive and metastatic transitional cell carcinoma (TCC) of secretor individuals. Increased synthesis or activation of normally quiescent glycosyltransferases in bladder tumors can result in the expression of aberrant tumor-associated blood group antigens. Immunohistochemical analysis has demonstrated that Lewis X (Le(x)) is not detected in normal adult urothelium except for occasional umbrella cells. However, papillomas, CIS and TCC expressed Le(x) in 84% of cases, regardless of grade, stage, blood type or secretor status of the individual. The presence of Le(x)-positive cells in bladder lavage specimens enhanced the detection of urothelial tumor cells, correctly identifying bladder tumors in 253/293 (86%) cases compared to a 63% sensitivity for cytology alone.(ABSTRACT TRUNCATED AT 250 WORDS)
