Changes in macrophage ectoenzymes associated with anti-tumor activity

Abstract

The phenotype of three ectoenzymes was determined for murine resident peritoneal macrophages, macrophages elicited in vivo by treatment of mice with thioglycollate, Corynebacterium parvum or pyran, and for resident macrophages activated in vitro by treatment with lymphokine. The relationship of these biochemical markers to macrophage antiviral and anti-tumor activity was established. Thioglycollate-elicited macrophages showed a unique ectoenzyme phenotype, with increased leucine aminopeptidase and alkaline phosphodiesterase I activity and markedly reduced 5'-nucleotidase activity as compared with resident macrophages. Thioglycollate-elicited macrophages exhibited extrinsic antiviral activity against herpes simplex virus but did not show anti-tumor activity. Another ectoenzyme phenotype was shared by macrophages elicited in vivo by treatment of mice with the immunomodulators or in vitro by treatment with antigen-specific lymphokine. These macrophage populations showed increased levels of leucine aminopeptidase but reduced levels of both 5'-nucleotidase and alkaline phosphodiesterase. This ectoenzyme phenotype was associated with the acquisition by the macrophages of selective anti-tumor activity. There appear to be clear distinctions in biochemical markers and functional properties among macrophages activated by different mechanisms.