STUDIES ON A NEW IMMUNOACTIVE PEPTIDE, FK-156: II. FERMENTATION, EXTRACTION AND CHEMICAL AND BIOLOGICAL CHARACTERIZATION

An interesting immunoactive peptide, FK-156, has been isolated from the fermentation broth of Streptomyces olivaceogriseus sp. nov. and Streptomyces violaceus. The compound was purified by column chromatography with activated carbon, ion exchange Sephadex and cellulose powder. FK-156, obtained as white powder, exhibits a wide variety of immunostimulatory activity in vivo and in vitro with experimental animals. Pretreatment of mice or rats with this peptide protected the animals against lethal infection with Escherichia coli and resulted in prolongation of life span of tumor bearing animals.