Figure 2.

Intact organisms are not required for induction of phagocyte serine protease inhibitor 9 (PI-9) messenger RNA (mRNA) by Mycobacterium tuberculosis. Alveolar macrophage (AM) monolayers were infected with M. tuberculosis strain H37Rv at several multiplicities of infection (MOIs) (1:1 to 50:1; bacteria/cell) or exposed to H37Rv lysate, a French press preparation of irradiated organisms (1–10 μg/mL). Cells were harvested at 4 hours, and expression of mRNA for PI-9 was assessed. As illustrated, both intact H37Rv (striped bars) and M. tuberculosis cell lysates (solid bars) induce PI-9 in a dose-dependent fashion, indicating that viable organisms are not essential for M. tuberculosis–induced expression of PI-9.