Ability of sera from mice treated with Ge-132, an organic germanium compound, to inhibit experimental murine ascites tumours.

Sera from C57Bl/6 mice treated orally with Ge-132 exhibited antitumour activity against Ehrlich (allogeneic) and RL male 1 (syngeneic) ascites tumours in BALB/c mice. Sera obtained from mice 24 h after Ge-132 administration displayed the greatest antitumour effect and this was dose dependent. Sera prepared from mice 12, 36, or 48 h after Ge-132 treatment had no protective effect. Circulating interferon (IFN) was induced at 24 h after administration of Ge-132 but was not detected in the sera at 12, 36, or 48 h after administration. The antiviral activity of sera from Ge-132-treated mice was inactivated by treatments with trypsin, low pH, and anti-IFN gamma antiserum. The inactivated preparations of serum IFN induced by Ge-132 did not exhibit antitumour activity when administered to tumour-bearing mice. These results suggest that antitumour activity in the sera of Ge-132-treated mice may be expressed through activities of Ge-132-induced lymphokine(s), such as IFN gamma.