Late effects of intravesical bacillus Calmette-Guérin immunotherapy on bladder mucosa infiltrating lymphocytes: an immunohistochemical study.

During intravesical bacillus Calmette-Guérin (BCG) treatment for the prophylaxis of recurrent superficial bladder carcinoma, patients typically show a local inflammatory response involving mainly T lymphocytes, most of which have the helper-induced phenotype (CD4+) (CD4+/CD8+ ratio > 1). To evaluate whether this immunophenotypic profile of the lymphocytes persists also after the completion of this immunotherapy, we examined bladder biopsy specimens during the posttreatment follow-up period of 24 patients, previously submitted to a 2-year BCG administration. The intensity of inflammatory response differed among the patients and in 10 of them even between the scar and the normal mucosa of the bladder. A reversal to the pretreatment CD4+/CD8+ ratio < 1 occurred in the majority of subjects, including the 3 patients with histologically confirmed tumour recurrence. In addition, 11 tumour-free patients showed prevailing CD4+ cells in the scar mucosa and prevailing CD8+ in the normal mucosa of their bladder or vice versa. From these findings it appears that the long-term host response to BCG does not depend exclusively on an intense, long-lasting local mononuclear immune reaction.