Experimental studies on BCG in hamsters

The effects of BCG in the treatment of superficial bladder cancer in man are known, but the mechanism is not quite well understood. Thirty-six hamsters received BCG through three routes: intravesical, intradermal and oral. Each group was composed of 12 animals; BCG was administered to 9 and only saline solution to 3 hamsters. BCG was given once a week for six weeks. The animals were sacrificed at 20, 30 and 65 days after the last administration of BCG. The anatomopathologic study revealed granulomatous reaction in the liver of 5 hamsters and in the spleen of 4 other animals of the intravesical group. In all groups that received BCG, hyperplasia of periarteriolar lymphoid tissue (T zone) of the spleen was observed. We support the view that BCG promotes a systemic reaction whatever the route of administration may be.