Scanning electron microscopy of immuno-gold labeled antigens associated with bladder cancer

Scanning electron microscopy (SEM), in the backscattered electron imaging (BEI) mode, has been used to study the topographical distribution of colloidal gold labeled antigens expressed on the luminal surface of the bladder urothelium in biopsies from three categories of patients: 1) normal controls; 2) patients with a history of bladder cancer but no pathological diagnosis at time of cystoscopy; and 3) patients with overt transitional cell carcinoma (TCC) of various histopathological stages and grades. Cold cup biopsies were processed for immuno-SEM according to a previously described method. Antigens under investigation were: 1) ABH blood group antigens; and 2) those identified by the following murine monoclonal antibodies (mAbs): LEU-M1, T16, 19A211, G4 and E7. In most cases labeling patterns were correlated with the surface features of the superficial urothelial cells as revealed in the secondary electron imaging (SEI) mode of the SEM. Results, to date, indicate that the immuno-gold labeling method is more sensitive than immuno-peroxidase, and that phenotypic heterogeneity of antigenic expression (or deletion) is a frequent observation of potential diagnostic or prognostic value.