In vivo autoregulation of macrophages. Analysis of superoxide anion production.

FERNÁNDEZ, M.L.; DURÁN, H.; DE REY, B.M.

Pucón

Congreso; VIII Congreso de la Pan-American Association for Biochemistry and Molecular Biology; 1996

We have reported that during the respiratory burst of the peritoneal macrophages the superoxide anion production per cell shows an inverse relation with the cell density of the elicited macrophages. This phenomenon is known as autoregulation. Phorbol esters (PMA) were used to induce the respiratory burst. Superoxide anion production ws measured by evaluating the formazan intracellular deposits generated by NBT reduction. Data on the superoxide production of the whole macrophage population was obtained spectrophotometrically at 572 nm. In the present study the response of the individual cells from various peritoneal populations of different cell densities was analyzed. The amount of formazan per cell and the correlation with cell-size changes which occur during PMA-activation were evaluated employing an automatic image analyzer (Ibas-Kontron/LANAIS-MEF). This analysis revealed that the decrease in individual cell response at higher cell densities was due to a significant increase in the amount of non-reactive cells. Concomitantly, the compartment of reactive cells remained unchanged irrespective of the cell density of the population. A direct correlation between cell size and superoxide anion production was also demonstrated. We conclude that variations in the non-responding cells compartment modulates the macrophage activation responses when excess cells are recruited to the peritoneum. Autoregulation of the macrophage population relies on the amount of non-reactive cells rather than on the differences in the reaction per cell.