Sequestration of Mycobacterium tuberculosis in tight vacuoles in vivo in lung macrophages of mice infected by the respiratory route

Abstract

Following aerosol infection of mice with Mycobacterium tuberculosis, single mycobacteria or pairs of bacilli were observed within individual phagocytic vacuoles bound by tightly apposed vacuolar membranes. The virulent organism was not observed free in the cytoplasm of the parasitized cells or in the extracellular space of the lung granulomata. This study indicates that in vivo, virulent mycobacteria survive and probably replicate within a unique tight vacuole in the infected phagocyte within the lung.

Role of the methylcitrate cycle in Mycobacterium tuberculosis metabolism, intracellular growth, and virulence

“…It is unclear why the methylcitrate cycle is required for growth of M. tuberculosis in murine bone marrow-derived macrophages ex vivo but not in the lungs of mice, where virtually all of the bacteria are located inside macrophages (Moreira et al, 1997). This paradox might be due to differences in the composition of fatty acid pools in bone marrow-derived macrophages versus pulmonary macrophages.…”

Cytolytic CD8+ T Cells Recognizing CFP10 Are Recruited to the Lung after Mycobacterium tuberculosis Infection

“…A minimal epitope (VESTAGSL; CFP10 [32][33][34][35][36][37][38][39] ) was identified that is presented by H-2K k to CD8 ϩ T cells primed during infection. From the same peptide library, a second epitope was identified (LAQEAGNFERISGDL; CFP10 [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] ) that is recognized by CD4 ϩ T cells. Both the CD4 ϩ and CD8 ϩ T cell responses to CFP10 evolved similarly in the spleen, lung, and draining LNs of infected C3H/HeJ mice.…”

“…Purified CD4 ϩ or CD8 ϩ T cells were cultured with the individual peptides and naive irradiated syngeneic splenocytes, and after 48 h, the culture supernatants were assayed for IFN␥ as a measure of T cell activation. Peptide 3 (LAQEAGNFERIS-GDL; herein referred to as CFP10 [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] ) was recognized by CD4 ϩ T cells and the overlapping peptides 7 (amino acid [aa] 27-39: TQIDQVESTAGSL) and 8 (aa 30-44: DQVESTAGSLQGQWR) were recognized by CD8 ϩ T cells from C3H mice, but not B6 or BALB/c mice ( Fig. 1).…”

“…The frequency of CFP10 11-25 -specific CD4 ϩ T cells and CFP10 32-39 -specific CD8 ϩ T cells in the PLNs, lung, and spleen was compared after infection of C3H mice with aerosolized M. tuberculosis. CD8 ϩ or CD8 Ϫ (e.g., CD4 ϩ ) T cells were purified from the infected organs 2-5 wk after infection and cultured with irradiated splenocytes from uninfected C3H mice with either the CFP10 [32][33][34][35][36][37][38][39] or CFP10 [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] peptides, respectively.…”

“…After infection of macrophages, M. tuberculosis survives and replicates in the phagosome. Just how bacterial antigens traffic from the phagosome to the cytoplasm where CFP10-specific CTL in the Lungs after Tuberculosis 1480 they can enter the MHC class I processing pathway is a matter of controversy; several mechanisms have been proposed (12,13). Once activated, CD8 ϩ T cells produce cytokines including IFN ␥ and TNF ␣ , which can activate macrophages and induce the production of nitrogen, oxygen radicals, and LRG47 (2,14,15).…”