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FIG 6 M. tuberculosis preferentially localizes to the cytosol in Il1r1−/− mice. (A and B) Fluorescence microscopy of 200-nm sections stained with DAPI (4′,6-diamidino-2-phenylindole) for nuclei (white) and anti-cell wall protein to detect M. tuberculosis (green) in granulomas in lung tissues of WT B6 mice (A) and Il1r1−/− mice (B) infected with M. tuberculosis for 28 days. (C) Immunogold labeling using LAMP1 to indicate lysosomal membranes in Il1r1−/− mice imaged using TEM. (C′) Schematic representation of panel C. M. tuberculosis is depicted in orange, host membranes are in blue, and the host nucleus is in pink. (D) Quantification of the localization of M. tuberculosis in B6 and Il1r1−/− lungs, here presenting cytosolic localization (see also Fig. S2D in the supplemental material). The analysis included 897 (WT) or 618 (Il1r1−/−) bacteria, and error bars indicate standard deviations based on in multiple granulomas of 2 WT B6 and 2 Il1r1−/− mice. KO, knockout.