Dual-parameter immunoflow cytometry--a new technique in the noninvasive diagnosis of bladder cancer

The introduction of monoclonal antibodies into the diagnosis of transitional cell carcinoma (TCC) has been a further step toward the use of biological parameters to support conventional cytological diagnosis of this tumor entity. Several investigators have demonstrated the high sensitivity and good specificity of immunocytology. Nevertheless this technique is hampered by the inconvenient and time-consuming microscopic analysis. The purpose of this study was to combine the advantages of immunocytology with the capabilities of an automated flow-cytometric system. Since all monoclonal antibodies (mAbs) currently used for immunocytology cross-react with granulocytes a preselection of urothelial cells becomes necessary for immuno-flow cytometry (immuno-FCM). Based on earlier analyses mAb Due AUT 2, reactive against urothelium and not against granulocytes, was chosen to preselect for urothelial cells. mAb Due ABC 3 was used to discriminate between normal and malignant urothelial cells. Initial experiments including 10 barbotage specimens from patients with histologically proven TCC and concomitant urinary tract infection yielded a high sensitivity (90%) of immuno-FCM. In 10 control patients with malignancies other than bladder TCC and benign diseases ABC 3 expression was not increased. Flow-cytometric examination of irrigation specimens from 10 patients with a history of bladder cancer but without cystoscopic and cytologic evidence of tumor recurrence showed abnormal results in 6 patients. Rebiopsy and/or cystectomy confirmed tumor recurrence in 5 of these patients and in 1 patient with negative immuno-FCM. Ongoing prospective trials will further define the clinical impact of this approach in the diagnosis and follow-up of patients with bladder cancer.