Macrophage migration inhibitory activity of mycobacterial growth inhibitory factor and the effect of a number of factors on mycobacterial growth inhibitory factor activity.

Mycobacterial growth inhibitory factor (MycoIF), which inhibits the intracellular multiplication of virulent tubercle bacilli within normal peritoneal macrophages in vitro, was tested for its ability to inhibit the migration of normal peritoneal exudate cells. The migration of peritoneal exudate cells was not inhibited by MycoIF. It was also shown that normal peritoneal macrophages infected with virulent Mycobacterium tuberculosis, strain H37Rv, required 72 h of incubation with spleen cell culture supernatant fluids containing MycoIF in order to inhibit intracellular bacillary multiplication. Treatment of infected macrophages with trypsin before their exposure to MycoIF abolished the ability of MycoIF to inhibit intracellular mutiplication of tubercle bacilli. Incubation of infected macrophages with goat anti-mouse globulin before their exposure to MycoIF also blocked the action of MycoIF.