Granuloma, tuberculous

T lymphocytes become activated over the course of 3 to 4 weeks, producing interferon-y (IFN-y) and other cytokines. These stimulate microbicidal macrophages to surround the tuberculous foci and form granulomas to prevent further extension.15 At this point, the infection is largely under control, and bacillary replication falls off dramatically. Any remaining mycobacteria are believed to reside primarily within granulomas or within macrophages that have avoided detection and lysis. Over 1 to... 

Fig. 24.4 Tuberculous epithehoid cell granuloma with Langhans giant cells and small central necrosis (N) additional steatosis of hepatocytes (HE)...

Mammalian tuberculin purified protein derivative (tuberculin PPD) is the active principle of old tuberculin. A small test dose in a healthy individual, given intracutaneously, is likely to produce only a little local pain and pruritus. If tuberculous infection is present, the local reaction is more marked, with vesiculation, ulceration, and even granuloma annulare or necrosis. 

The role of chemokines in granulomatous disease of the pleura has been extensively studied in mberculous pleurisy (16,25-28). Tuberculous pleural fluids contain a significant proportion of mononuclear phagocytes and lymphocytes that are responsible for the initiation of the granulomatous inflammatory response and the localization of mycobacteria into granulomas (16,29,30). 

The a-subunit of the clotting factor XIII (FXIIIa) has been shown in tuberculous infections as well as in sarcoidosis to be synthesised by macrophages identified by immunohistochemistry predominantly in the periphery of granulomas, whereas the centres were generally devoid of these cells (Probst-Cousin et al. 1997). 

Bergeron A, Bonay M, Kambouchner M, et al. Cytokine patterns in tuberculous and sarcoid granulomas correlations with histopathologic features of the granulomatous response. J Immunol 1997 159(6) 3034-3043. 

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