ISOLATION OF A NONTOXIC LIPID-A FRACTION CONTAINING TUMOR-REGRESSION ACTIVITY

  • 1 January 1981
    • journal article
    • research article
    • Vol. 41  (7) , 2654-2657
Abstract
Galanos-type endotoxin obtained from the heptose-less mutant of Salmonella typhimurium was converted to Lipid A by 2 cycles of treatment with sodium acetate, pH 4.5, at 100.degree. C and separated on a DEAE-cellulose column into several fractions (fractions III to VII). Tumor regression studies with strain 2 guinea pigs and syngeneic line 10 hepatocellular carcinoma showed that all fractions were effective when combined with trehalose dimycolates and an additional tumor regression factor (previously designated ACP) and incorporated into oil droplets (78-100% cures). A low polar fraction (fraction IV) was relatively nontoxic [the medium lethal dose for 11-day-old chick embryos inoculated i.v.(CELD50) was > 10 .mu.g] and nonpyrogenic [the dose estimated to give a fever index (area under fever curve) of 40 cm/in rabbits when 1 h and 1.degree. C are plotted as 1 (Fl40 was 5 .mu.g] as compared to the unfractionated Lipid A (CELD50 of 0.0546 .mu.g; Fl40 of 0.046 .mu.g). All other fractions were toxic and pyrogenic and caused severe endotoxic shocks when combined with N-acetylmuramyl-L-seryl-D-isoglutamine and injected i.v. into guinea pigs. Fraction IV plus N-acetylmuramyl-L-seryl-D-isoglutamine did not cause endotoxic shock. The phosphate content of fraction IV was 1/2 of that detected in the toxic fractions.