Blood group antigens in transitional cell tumours of the urinary bladder. An immunohistochemical study.

Patients presenting histologically identical non-invasive tumours of the urinary bladder suffer a variable unpredictable clinical course, making the identification of prognostic markers relevant in the clinical setting. Recent histochemical studies have demonstrated that changes in cell surface carbohydrates during malignant transformation involve the blood group antigens. These oligosaccharides, initially defined on erythrocytes, are widely distributed in human tissue including human urothelium. This study was conducted in order to evaluate the prognostic value of blood group antigen determination in superficial bladder cancer. The aims of the present study were: 1. To standardize the immunohistochemical staining technique for blood group antigens, 2. To investigate the pattern of blood group antigen expression in non-neoplastic urothelium, the genetic heterogeneity, 3. To examine changes in the blood group antigen expression in bladder cancer, and 4. to assess the prognostic value of blood group antigen expression in superficial bladder cancers of morphological similar appearance. The ABH, Lewis, and Thomsen-Friedenreich (T) blood group antigens were studied by means of the Tween 20-modified indirect immunoperoxidase staining technique. Serial dilutions of antibodies and lectins were applied on dewaxed routinely processed tissue sections of normal ureters and transitional cell tumours. The reciprocal value of the highest dilution of antibody and lectin still giving staining defined the endpoint titer and allowed semiquantitative estimation of antigen content. In non-neoplastic urothelium the ABH, Lewis and T blood group antigens were heterogeneously expressed, and the expression correlated to the Lewis blood type. This indicates 1) a genetic regulated synthesis of ABH and Lewis blood group antigens similar to that operating in saliva, other secretions, epithelia, and erythrocytes, 2) a possible linkage between ABH-, Lewis-, and T antigen systems, if steric hindrance can be excluded. Based on the above findings in non-neoplastic urothelium the deviation in tumours from normal blood group antigen expression was quantified on a scale from 0 (normal) to 3 (total loss) for each antigen system separately. All scores were related to histological stage and grade suggesting a parallelism between morphological dedifferentiation and the degree of abnormal blood group expression. In superficial low grade tumours only A and Lewis a scores were related to prognosis. This held only true for patients with tumours of normal or nearly normal A and Lewis a antigen expression (scores 0 and 1), who had a favorable course as regards invasive recurrence and/or papillomatosis within 5 years. Prediction of an unfavorable outcome was not possible. Only a small number of superficial tumours exhibited normal blood group antigen expression.(ABSTRACT TRUNCATED AT 400 WORDS)