Prevention of tumor growth after intradermal injection of BCG extracts: a comparison of results in strain-2 guinea pigs from the National Institutes of Health and from the National Jewish Hospital and Research Center.

Line 10, a transplantable hepatocellular carcinoma, was obtained originally from an NIH strain-2 male guinea pig fed diethylnitrosamine. The antitumor activity of BCG and BCG extracts was evaluated in strain-2 guinea pigs obtained both from NIH and the National Jewish Hospital and Research Center (NJH). Animals were immunized with these materials and then tested for their capacity to resist the growth of intradermally injected line-10 tumor cells. Tumor growth was not prevented in 18 NIH animals immunized with living BCG. No tumor growth occurred in 1 of 22 NIH animals immunized with a residue that remained after exhaustive methanol extraction of BCG and in 1 of 44 NIH guinea pigs immunized with BCG extracts. In contrast, tumor growth was prevented in 13 of 22 similarly immunized NJH guinea pigs.