Histopathology of BCG and thiotepa treated bladders.

In an effort to characterize the pathophysiological differences between the modes of action of BCG and thiotepa in the treatment of superficial bladder cancer, normal female rats received weekly intravesical instillations of both agents. The animals were sacrificed and their bladders were examined pathologically to determine if there were histological differences between the cellular infiltrates found in the BCG and thiotepa treated bladders. Mononuclear cells, particularly T-cells, predominated in the BCG treated bladders whereas polymorphonucleated cells predominated in the thiotepa treated bladders suggesting that there may be an immune aspect to the former therapy. The presence of T-cells following BCG therapy suggest a T-cell mediated immune response.