Effect of bestatin on mouse immune system and experimental murine tumors.

Effect of bestatin on the establishment of delayed-type hypersensitivity (DTH) to sheep red blood cells (SRBC) and oxazolone was examined in normal and immunity-impaired mice. Administration of a low dose of bestatin (0.1 approximately 100 microgram/mouse) augmented DTH to SRBC and restored their impaired DTH to oxazolone. The effect of bestatin in the mouse was age-dependent. Bestatin retarded the growth of slow growing solid tumors of Gardner lymphosarcoma and IMC carcinoma and the effect was influenced by the time of the administration and the number of cells inoculated. Bestatin enhanced the antitumor action of the antitumor antibiotics, bleomycin and adriamycin. Bestatin also retarded the induction of skin cancer by 20-methylcholanthrene.