title: Role of distinct subpopulations of peritoneal macrophages in the regulation of reactive oxygen species release.
abstract: It has been reported in vitro that during the respiratory burst of phagocytic cells the superoxide anion production per cell shows a negative relation with the cell density. This process has been described as autoregulation. The aim of this work was to analyze the superoxide anion production in thioglycollate-elicited peritoneal macrophage exudates to evaluate the importance of the peritoneal cavity environment in the autoregulation process. 12-O-tetradecanoylphorbol-13-acetate (PMA) was used to stimulate the respiratory burst and superoxide anion production was measured evaluating the intracellular formazan deposits that precipitate as a result of nitro blue tetrazolium (NBT) reduction. We have demonstrated a negative correlation between superoxide anion production and cell density in the peritoneal cavity in macrophages challenged with PMA. The response of individual cells was analyzed by means of an image analyzer, measuring the amount of formazan per cell and cell-size changes during the process of activation. The results revealed that the decrease in individual cell response as a function of higher cell densities were due to a significant increase in the amount of basal reaction macrophages. Concomitantly, the number of reactive cells remained unchanged irrespective of the cell density of the population. A direct correlation between cell size and superoxide anion production was observed. This phenomenon was demonstrated in SENCAR and Balb/c strains. However, macrophages from SENCAR mice showed greater superoxide anion production than those from Balb/c. The differences between strains could be associated to the increased sensitivity to PMA tumor promotion of SENCAR mice. Based on this property, macrophages from SENCAR mice were stimulated with opsonized zymosan, a particulate stimulus that reflects the interaction macrophage-microorganism during the phagocytic process. This data will contribute to the knowledge of infection control. We conclude that variations in basal reaction cells modulates the macrophage activation response when excess macrophages are recruited to the peritoneum. This is demonstrated using different stimuli, thus suggesting that this response may be applied to a wide variety of stimuli-macrophage interactions. The differences between strains may be associated to the increased sensitivity to PMA tumor promotion of SENCAR mice.
authors.affiliation: Radiobiology Department, National Atomic Energy Commission, Tandar Laboratory, Pcia. de Buenos Aires, Argentina.
authors.forename: M L
authors.initials: ML
authors.lastname: Fernández
authors.forename: H A
authors.initials: HA
authors.lastname: Durán
authors.forename: S E
authors.initials: SE
authors.lastname: O'Connor
authors.forename: R L
authors.initials: RL
authors.lastname: Cabrini
authors.forename: B L
authors.initials: BL
authors.lastname: Molinari
mesh_terms: D000818:Animals; D002452:Cell Count; D048429:Cell Size; D007091:Image Processing, Computer-Assisted; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D018632:Mice, Inbred SENCAR; D008815:Mice, Inbred Strains; D017382:Reactive Oxygen Species / Q000378:metabolism*; D016897:Respiratory Burst; D013053:Spectrophotometry; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013778:Tetrazolium Salts; D013864:Thioglycolates / Q000494:pharmacology; D015054:Zymosan / Q000494:pharmacology
chemical_list: D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013864:Thioglycolates; D013481:Superoxides; D015054:Zymosan; D013755:Tetradecanoylphorbol Acetate