A biological study on hot-water extract from delipidated Mycobacterium bovis strain BCG.

The biological activity of a hot-water extract from delipidated BCG, designated as HSA (Hot-water Soluble Adjuvant), was investigated. The HSA did not induce hyperreactivity to bacterial endotoxin. The hot-water extract from which nucleic acids had been removed by streptomycin (SM-HSA) was found to enhance the delayed-type hypersensitivity as evidenced by the results of footpad reaction of mice. The HSA and SM-HSA could be injected to mice by an intraperitoneal route for 20 consecutive days without undesirable side effects. A comparative study was made on the effects of HSA in relation to the duration and doses of treatment with HSA using the ddI mice inoculated with Sarcoma-180. The most remarkable effect was observed when 0.25 mg of HSA had been injected for 20 consecutive days. Also SM-HSA was found to exert antitumor activity when applied in the same manner as above. These results suggest that the presence of nucleic acids is not related to the biological and antitumor activities of the hot-water extract.