Fig 1. B cell-deficient μMT mice exhibit diminished lung infiltrates relative to WT C56BL/6’s in chronic TB.

WT and B cell-deficient μMT mice were aerogenically infected with 100 CFU of M. tuberculosis Erdman and tissues analyzed by examination of H&E-stained lung sections at 12 weeks (A) and 24 weeks (C) post-infection. Quantification of the number of total lung cells was also carried out at the same time intervals post-inoculation (12 weeks, (B); 24 weeks (D)). These histological studies and enumeration of total lung cell numbers showed that in chronic TB, B cell-deficiency is associated with diminished granulomatous inflammatory response; n = 3–4 mice per group per time interval. The results depicted in (A) and (C) are representative of lung sections from 3 mice examined. The data shown in (B) and (D) denote the mean ± SEM (standard error mean). The results shown in (A, B, C, and D) are representative of 2 experiments. (E) Lung mycobacterial burden as measured by culturable bacilli 4, 12, and 24 weeks after a 100 CFU Erdman aerogenic challenge, demonstrating that bacillary loads in μMT and WT mice are comparable throughout the course of infection; n = 4 to 5 mice per group. The data depicted denote the mean ± SEM. The results shown are representative of two experiments. (F) B cell-deficient μMT mice exhibited increased median survival relative to WT controls after a 100 CFU aerosol Erdman infection (median survival time: 324 days versus 272 days); n = 10 mice per group. The result is demonstrable in three independent experiments.