[Change in activity of enzymes for purine metabolism and RNA and DNA biosynthesis in macrophages, reflecting impairment of their functions in neoplastic growth].

The changes in the biochemical parameters of peritoneal macrophages and their coupling to the secretory and phagocytic functions in CH3A mice during the growth of the reinoculated solid hepatoma 22a were studied. The DNA and RNA synthesis during the active tumour growth was more intense than that in resident macrophages. The activity of uridine kinase increased up to 156.0 +/- 12.0 nmol/hour/10(8) but was absent in resident macrophages. This was accompanied by a 7.2-fold increase of interleukin-1 synthesis as determined by the [3H]thymidine incorporation into thymocyte DNA in response to concanavalin A administration to C3H mice. Similar changes were observed in peptone-stimulated macrophages. A specific feature of macrophages from tumour-bearing mice was the impairment of activity of purine exchange enzymes and the efficiency of phagocytosis that were unobserved in peptone-stimulated macrophages. The activity of adenosine deaminase and purine nucleoside phosphorylase was inhibited as a result of their preincubation with zymosan, a phagocytosis-stimulating agent. This was accompanied by a significant decrease of the first chemiluminescence peak resulting from disturbances in Fc-reception. Macrophages of tumour-bearing animals possessed an increased 2.2-fold activity of membrane-bound AMP 5'-nucleotidase concomitant with the lack or decrease of the amplitude of the second chemiluminescence peak reflecting the disturbances in digestion resulting from phagocytosis.