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We present two monoclonal antibodies (mab), Mano 4/4 and 486 P3/12, directed against tumor-associated antigens of different subpopulations of transitional cell bladder carcinoma tumors. A detailed description is given concerning their reactivity patterns in an ELISA assay against different cell lines. Using immunohistochemical staining against normal bladder mucosa, mab Mano 4/4 reacts with distinct cells in the basal layer and mab 486 P 3/12 recognizes single cells in the superficial layer. Analysing different transitional-cell carcinomas, mab Mano 4/4 reacts with 17 of 20 and mab 486 P 3/12 with 17 of 19 bladder tumors. It is emphasized that both mabs may add new information in respect to a better characterization of the heterogeneity of bladder carcinoma. A biochemical characterization of the mabs and their corresponding antigens is given. Mab Mano 4/4 is directed against a 28 kD glycoprotein and mab 486 P 3/12 is reacting with a 200 kD glycoprotein belonging to the family of CEA-like proteins.

Monoclonal antibodies directed against tumor-associated antigens of bladder carcinoma were used to identify tumor cells in bladder washout specimens of 40 patients with bladder carcinoma (group 1), 41 with no bladder disease or with urinary tract infections (group 2), 41 who received long-term mitomycin C instillation therapy after excision of the tumors (group 3) and 39 who received no prophylaxis after excision of the tumors (group 4). In all groups the same bladder washout specimen was used for standard urinary cytological and immunocytological tests. True positive results were obtained in 90 per cent of the patients in group 1 according to our immunocytological criteria and in 43 per cent according to standard cytology studies. No urine specimens in group 2 (controls) were immunocytologically positive, while 16 of 41 in group 3 and 17 of 39 in group 4 were positive immunocytologically but only 4 and 5, respectively, were positive according to standard cytology studies. Further followup of these patients will show whether cells positive for monoclonal antibody 486 P 3/12 will permit early detection of recurrent bladder cancer and whether one can identify patients who require prophylaxis after removal of the superficial bladder tumors.