AID^−/−µS^−/− mice have an altered B cell population in the lung and are more susceptible to aerosol infection with Mtb.

<p>C57BL/6 (filled circles) and AID^−/−µS^−/− mice (opened circles) were infected with Mtb H37Rv via the aerosol route. (A–C) At day 30 of infection, B cells (gated on live lymphocytes and CD19 expression) were analyzed for the expression of IgM and IgD by flow cytometry. The frequency (A) and total number of CD19⁺ cells, CD19⁺IgD⁻IgM⁺ cells and CD19⁺IgD⁺IgM⁺ cells in the lung (B) and spleen (C) was calculated. (D) The bacterial burden was determined in lungs and spleen over time (<i>n</i> = 4). (E) Survival of infected mice was determined over the course of the experimental infection (<i>n</i> = 5). (A–E) One experiment representative of at least three independent experiments is shown *, p<0.05**, p<0.01; ***, <i>p</i><0.001 by Student’s <i>t</i> test. (F–H) C57BL/6 (filled circles), AID<i>^−/−</i> (F), µS^−/− (G) and µMT (H) mice (opened circles) were infected, and the bacterial burden was determined in the lungs and spleen over time (<i>n</i> = 4–8). Data sets from a total of two experiments were combined. *, p<0.05; ***, p<0.001 by Student’s <i>t</i> test.