STIMULATION OF PHOSPHATIDYLINOSITOL TURNOVER IN THE MACROPHAGE PLASMA-MEMBRANE - POSSIBLE MECHANISM FOR SIGNAL TRANSMISSION

  • 1 January 1979
    • journal article
    • research article
    • Vol. 37  (3) , 689-696
Abstract
The effect of various stimuli on the rate of phosphatidylinositol turnover by mouse peritoneal macrophages was studied by measuring the incorporation of myo-[2-3H]-inositol. The macrophage-activating agents endotoxin and Corynebacterium parvum [Propionibacterium acnes] caused an increase in phosphatidylinositol turnover while inert particles (Staphylococcus albus [S. aureus], latex and carbon) had no effect even though they were phagocytosed. The stimulation by C. parvum was dependent on the presence of T [thymus-derived] cells. T lymphocytes from normal mice and mice immunized with C. parvum were equally effective and normal and immune T cells could be stimulated by C. parvum as indicated by an increased uptake of [6-3H]-thymidine. Supernatants from normal or immune spleen cells cultured with and without C. parvum were ineffective and could not replace intact T cells, indicating that cell to cell contact is required or a labile factor that acts over a short range. The time course of stimulation of phosphatidylinositol turnover by macrophages was studied using endotoxin. The rate of turnover increased slowly over a few hours and was still rising at 6 h but decreased again at 24 h. The increase in bacteriostatic activity against Listeria monocytogenes by macrophages exposed to endotoxin took longer to develop and was more marked at 24 h than at 4 h. The differences between pathways leading to phagocytosis or chemotaxis and those resulting in activation were discussed.