Naïve splenocytes cultured with <i>Mtb</i>-infected Mφ produce IFN-γ and suppress bacterial replication.

<p>(A) <i>Mtb</i>-infected Mφ secrete IL-12. Uninfected (open bars) and <i>Mtb</i>-infected (solid bars) were cultured in the presence or absence of splenocytes (Spln). IL-12p40 was measured after 24 hrs. Bars represent the mean+/−SD of triplicate cultures. (B) <i>Mtb</i>-infected Mφ stimulate IFN-γ secretion by splenocytes. Uninfected (open bars) and <i>Mtb</i>-infected (solid bars) were cultured in the presence or absence of splenocytes. IFN-γ was measured 24 hrs after coculture. The bars represent the mean+/−SD of triplicate cultures. (C) Coculture of splenocytes with infected Mφ leads to reduced <i>Mtb</i> replication. <i>Mtb</i>-infected Mφ were cultured in the presence or absence of splenocytes from uninfected mice for 3 days and then CFU were determined. Bar represents mean+/−SD from replicate cultures (n = 6). (D) Naïve splenocytes reproducibly suppress intracellular <i>Mtb</i> replication. To determine the average CFU reduction, the data from 18 independent experiments were normalized by setting the CFU recovered from the infected Mφ cultured alone to 100%. Bars, mean±SEM.