Clinical Isolates of Mycobacterium tuberculosis Differ in Their Ability to Induce Respiratory Burst and Apoptosis in Neutrophils as a Possible Mechanism of Immune Escape

Figure 2

PMN apoptosis induced by different Mtb strains. PMNs (3 × 10⁶/mL) were cultured in media alone (control, —) or stimulated with Mtb strains (H37Rv, LAM, Ra, H, and M) at 1 : 2 Mtb : PMN ratio and parameters of apoptosis were evaluated by flow cytometric analysis. (a) Expression of Annexin V-FITC (AV-FITC) on PMN cultured for 18 h. Results are expressed as media ± SEM of percentage of positive cells (𝑛=20). Control (—) versus LAM, Ra, and H: ^∗∗𝑃<0.001; H37Rv: ^∗𝑃<0.01; LAM and Ra versus other strains: ^#𝑃<0.001. (b) Intracellular expression of activated cytoplasmic protein caspase-3 in PMN after 5 h culture with or without Mtb stimulation. Results are expressed as media ± SEM of MFI. Control (—) versus LAM and Ra: ^∗∗∗𝑃<0.001; H37Rv: ^∗∗𝑃<0.01; H ^∗𝑃<0.05; LAM and Ra versus other strains: ^#𝑃<0.001. (c) The percentage of fresh (0 h) and 16 h cultured cells expressing FcRIIIb (CD16) was measured. 0 h versus control: ^#𝑃<0.0002; control vesrus Mtb strains: ^∗𝑃<0.0001.

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