FIG 4.

Macrophage restriction of M. tuberculosis elicited by all-trans-retinoic acid can be relieved by cholesterol or odd-chain fatty acids. (a, b) Control of autobioluminescent Mtb treated with ATRA and various concentrations of water-soluble cholesterol, in MO-GMCSF at 5.5 days (a) or in BMDM at 9.5 days (b). (c to h) Comparison of Mtb loads by CFU assay at 5 days in MO-GMCSF (c to e) or BMDM (f to h). ATRA was added at 10 μM, and fatty acids were added complexed to essentially fatty acid-free bovine serum albumin (BSA) at a 3:1 ratio. All infections were performed at a multiplicity of infection of 2 bacteria per macrophage, with all samples in triplicate (3 donors for MO-GMCSF). DMSO was used at 0.1% in all comparisons. Statistics were performed using ordinary one-way ANOVAs with Šídák’s (a) or Dunnett’s (b) multiple-comparison test, ratio paired t tests (c to e), or unpaired t tests (f to h). *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001; ns, not significant.