Mycobacteria and macrophage activation.

Recent studies that challenged some older concepts have led to the following conclusions: 1) During an infection of mice with M. bovis, BCG macrophages are activated according to certain criteria, but the increase in their bactericidal or bacteriostatic activity is limited to a small number of bacteria species; 2) interferon-gamma can activate macrophages in vitro and in vivo, but these cells do not exhibit increased bactericidal activity; 3) a 65-kDa protein of mycobacteria can activate macrophages in vivo to a limited degree only; and 4) granulocytes stimulated with interferon-gamma kill ingested M. fortuitum more efficiently than normal granulocytes.