Mycobacterium tuberculosis Multidrug-Resistant Strain M Induces Low IL-8 and Inhibits TNF-α Secretion by Bronchial Epithelial Cells Altering Neutrophil Effector Functions

Figure 1

Mycobacterium tuberculosis strains invade and replicate within Calu-6 cells. Calu-6 cell monolayers were infected with H37Rv (●) or M (▲) strains at a MOI of 5 for 2 h and (a) either harvested and lysed to determine bacterial uptake or cultured for further 96 h to allow intracellular replication. Cells were lysed at each time point and serial dilutions were plated to determine CFU. Total CFU from Calu-6 cells cultured at 0 h or 96 h upon infection; mean ± SEM are shown () or (b) allow intracellular replication for further 18 h to determine cell death by measuring Annexin V and FVD eFluor 780 expression by flow cytometry. Results are expressed as percentage of early apoptotic (Annexin Vpos/FVD eFluor780neg), late apoptotic (Annexin Vpos/FVD eFluor 780pos), or necrotic cells (Annexin Vneg/FVD eFluor 780pos). H₂O₂ was used as apoptosis positive control. Gate strategy for Calu-6 cells is shown.

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