Characterization of cellular infiltrates in the rat urinary bladder following BCG and thiotepa intravesical therapy.

We examined rat urinary bladders following intravesical administration of BCG and thiotepa. BCG administration resulted in a relatively greater increase in the mucosal infiltration of mononuclear cells relative to polymorphonuclear cells (P less than 0.01) compared to the thiotepa treated bladders. This finding suggests that the mode of action of the therapeutic effects of these agents may be different. These results may also suggest that the mechanism of action of BCG might be immunologic in nature.