ROLE OF DISTINCT SUBPOPULATIONS OF PERITONEAL MACROPHAGES

FERNÁNDEZ ML, DURÁN HA, O’CONNOR SE, CABRINI RL, MOLINARI BL

FREE RADICAL BIOLOGY AND MEDICINE

Elsevier

Año: 1999 vol. 27 p. 797 - 809

0891-5849

Abstract—It has been reported in vitro that during the respiratory burst of phagocytic cells the superoxide anionproduction per cell shows a negative relation with the cell density. This proccess has been described as autoregulation.The aim of this work was to analyze the superoxide anion production in thioglycollate-elicited peritoneal macrophageexudates to evaluate the importance of the peritoneal cavity environment in the autoregulation process. 12-Otetradecanoylphorbol-13-acetate (PMA) was used to stimulate the respiratory burst and superoxide anion production wasmeasured 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 theperitoneal cavity in macrophages challenged with PMA. The response of individual cells was analyzed by means of animage analyzer, measuring the amount of formazan per cell and cell-size changes during the process of activation. Theresults revealed that the decrease in individual cell response as a function of higher cell densities were due to asignificant increase in the amount of basal reaction macrophages. Concomitantly, the number of reactive cells remainedunchanged irrespective of the cell density of the population. A direct correlation between cell size and superoxide anionproduction was observed. This phenomenon was demonstrated in SENCAR and Balb/c strains. However, macrophagesfrom SENCAR mice showed greater superoxide anion production than those from Balb/c.The differences betweenstrains could be associated to the increased sensitivity to PMA tumor promotion of SENCAR mice. Based on thisproperty, macrophages from SENCAR mice were stimulated with opsonized zymosan, a particulate stimulus that reflectsthe interaction macrophage–microorganism during the phagocytic process. This data will contribute to the knowledgeof infection control. We conclude that variations in basal reaction cells modulates the macrophage activation responsewhen excess macrophages are recruited to the peritoneum. This is demonstrated using different stimuli, thus suggestingthat this response may be applied to a wide variety of stimuli–macrophage interactions. The differences between strainsmay be associated to the increased sensitivity to PMA tumor promotion of SENCAR mice.