Dissociative effects of a novel immunomodulating agent (CP-20, 961) on host defenses of mice

The antimicrobial and antitumor effects of CP-20,961, a synthetic lipoid amine with immunomodulating properties, were investigated. Mice given CP-20,961 ip seven or three days before challenge with ip Listeria monocytogenes had a lower mortality than control mice. By contrast, CP-20,961 did not protect against lethal challenges of either Salmonella typhimurium or Toxoplasma gondii. In parallel with the in vivo studies, peritoneal macrophages from CP-20,961-injected mice inhibited multiplication of L. monocytogenes but not T. gondii. Further studies demonstrated that CP-20,961 protected mice against an ip challenge of P815 tumor cells as measured by survival time. This correlated with the ability of stimulated peritoneal macrophages to inhibit (3H-TdR uptake inhibition) and kill (Cr51 release) P815 cells in vitro. These data indicate that CP-20,961 affords protection against an ascitic mastocytoma tumor line and at least one, but not all, intracellular pathogens. The dissociation of the immunomodulating effect, which was reflected in peritoneal macrophage function, may be characteristic of this new class of immunomodulators.