Inhibition by tuftsin of Rauscher virus leukemia development in mice.

The antitumor effect of tuftsin, the natural phagocytosis-stimulating peptide, on leukemia induced by Rauscher murine leukemia virus (R-MuLV) was studied in vivo in SWR inbred mice. Tuftsin was found capable of significantly increasing the survival of R-MuLV-infected mice. The peptide, when injected both ip and iv into mice, exerted its activity in a dose- and time-dependent manner. Optimal antitumor activity was achieved upon administration of 25 micrograms tuftsin 4 days before R-MuLV inoculation.