Enhanced oxygen metabolism of peritoneal macrophages in the presence of murine neuroblastoma cells is partly caused by enkephalins.
A bioluminescent technique was used to show that murine neuroblastoma (NB) cells or cell-free extracts (H variant) were able to enhance the release of reactive oxygen intermediates (ROI) from peritoneal macrophages in vitro. L-variant NB cells were ineffective. Physiological concentrations of met-enkephalin produced the same effect in vitro but not leu-enkephalin. When both H- and L-variant cells, or their extracts, were incubated together with macrophages, ROI production was not increased. Similar findings were detectable when met- and leu-enkephalin were cultured together with macrophages. In vivo, preliminary studies gave the same results. The concentration rate of met- to leu-enkephalin was higher in H-variant than in L-variant NB cells. We conclude from our results that met-enkephalin can enhance the release of ROI from peritoneal macrophages. The difference in the effects produced by the H and L variants is due to differences in the concentrations of enkephalins released.
Willems
J
J
Interdisciplinary Research Center, K.U. Leuven, Kortrijk, Belgium.
Leclercq
G
G
Joniau
M
M
D000818:Animals; D000940:Antigenic Variation; D004745:Enkephalins / Q000502:physiology*; D005260:Female; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009447:Neuroblastoma / Q000032:analysis / Q000276:immunology / Q000473:pathology*; D010101:Oxygen Consumption / Q000187:drug effects; D010529:Peritoneal Cavity / Q000166:cytology*; D014020:Tissue Extracts / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D004745:Enkephalins; D014020:Tissue Extracts