Histopathology of Tumor Regression After Intralesional Injection of Mycobacterium bovis. II. Comparative Effects of Vaccinia Virus, Oxazolone, and Turpentine2

Abstract

Treatment of transplanted syngeneic tumors in guinea pigs with a single sensitization by vaccinia virus, oxazolone, or turpentine was compared to therapy with Mycobacterium bovis strain bacillus Calmette-Guérin (BCG). Hepatocarcinoma cells, transplanted intradermally, had become established tumors with regional lymph node metastases before treatment. Except for topical painting of oxazolone, all other treatments were administered by intralesional injections. The established syngeneic tumor regressed in the skin site after a single injection of live BCG, and regional lymph node metastases were eliminated. The effective antitumor mechanism in the BCG-treated animals was a granulomatous reaction, both at the skin site and in the regional lymph node, characterized by an intense proliferation of stromal reticuloendothelial components and histiocytes. Cellular reactions in the regional lymph nodes draining tumors treated with vaccinia virus or oxazolone, which were characteristic of the development of delayed-type hypersensitivity, were not detrimental to the tumor and did not alter metastatic growth. The turpentine-induced inflammatory reaction at the tumor site was also ineffective in suppressing tumor growth. Both turpentine and oxazolone treatments, on the other hand, enhanced tumor growth in the skin.