Natural killer (NK) cell assay within bladder mucosa of patients bearing transitional cell carcinoma (TCC) after interferon (IFN) therapy: an immunohistochemical and ultrastructural study

Abstract

The authors studied the number and the ultrastructural evidence of NK cell activation in the non-involved urothelium in patients with transitional cell carcinoma (TCC) of the urinary bladder, before and after transurethral resection (TUR) and interferon (IFN) therapy. Eight male patients, free of recurrence 1 year after TUR and IFN-a2b therapy, were studied. Each patient received 22 instillations of 50MU of IFN-a2b over a period of 1 year. Two specimens from the non-involved urothelium, one adjacent to and another away from the tumour, were obtained before and after therapy, for immunohistochemical and ultrastructural studies. The number of NK cells was evaluated immunohistochemically in paraffin sections with the CD57 monoclonal antibody, and their activation was detected by routine electron microscopy processing. Before treatment, few NK cells were randomly found in the lamina propria. At the end of therapy, however, their number increased and NK cells were found to infiltrate the urothelium, a finding that was not observed before treatment. The number of NK cells did not correlate with the degree of the inflammatory infiltrate of the mucosa. Moreover, the ultrastructural study revealed activation of NK cells with enhanced cytolytic activity. IFN therapy increases the number and promotes the activation of NK cells within the bladder mucosa. This finding could be of clinical significance in the prevention of tumour recurrence, given that NK cells enhance the immunological defense mechanisms of the bladder.