WS1279, a novel lipopeptide isolated from Streptomyces willmorei. Biological activities.

WS1279, a new lipopeptide isolated from the fermentation broth of Streptomyces willmorei No. 1279, stimulated the proliferation of mouse bone marrow cells in vitro and accelerated the recovery of granulocyte counts in bone marrow from leukopenia induced by mitomycin C (MMC) in mice. The glycerylcysteine moiety of WS1279 is necessary and the lipid peptide structure is required for manifestation of full stimulating activity in vitro. WS1279 was the most effective on the proliferation of bone marrow cells among the tested immunostimulants in vitro. However, the effect of WS1279 on restoration of reduced granulocyte counts in MMC-induced leukopenia in mice was less than that of FK-565, lipopolysaccharide, picibanil or forphenicinol. WS1279 augmented host resistance to infection with Staphylococcus aureus 47 in normal and immunosuppressed mice.