Effect of purified protein derivative and sonicates of Mycobacterium leprae and Mycobacterium bovis BCG on thromboplastin response in human monocytes in vitro.

Human monocytes isolated from peripheral blood responded with increased thromboplastin expression upon stimulation in vitro with three mycobacterial antigens: tuberculin purified protein derivative and sonicates of Mycobacterium boviS BCG and Mycobacterium leprae. The stimulating principle of mycobacteria is probably a cell wall constituent since crude extracts of cell walls were 2.5 to 25 times more potent in stimulating thromboplastin synthesis than were whole sonicates. This thromboplastin response was inhibited by inhibitors of RNA and protein synthesis, dexamethasone, and agents that caused elevation of intracellular cyclic AMP. The presence of lymphocytes did not enhance the monocyte thromboplastin response significantly during the first 24 h of incubation. For M. bovis BCG and M. leprae sonicates, the thromboplastin response correlated with general activating effects measured by determining the release of lysozyme and beta-glucuronidase. The role of thromboplastin in chronic inflammatory reactions is discussed.