Pine Cone Antitumor Substances Stimulate Cytotoxic Factor Production in Young Mice, but not in Aged or Tumor-Bearing Mice

Abstract

Mice produce a cytotoxic factor (CF) against mouse fibroblast L-929 cells. Production of this factor was investigated in young, aged, and tumorbearing mice. Intravenous administration of pine cone antitumor substances (Fr. VI or VII), followed by OK-432, caused higher amounts of CF to be produced in ICR mouse serum fractions. Significant loss of CF activity by heat or trypsin treatment suggests that the active principle (s) of the induced f actor (s) might be proteineous substance (s) . Tumor-bearing and aged mice produced much lower amounts of CF activity than normal and young mice, when stimulated with pine cone extracts and OK-432.