Innate Invariant NKT Cells Recognize Mycobacterium tuberculosis–Infected Macrophages, Produce Interferon-γ, and Kill Intracellular Bacteria
Figure 6
iNKT cells are sufficient to inhibit intracellular bacterial replication.
(A) Mtb-infected Mφ were cultured alone or with WT splenocytes (spln) or with iNKT cells. Bacterial growth in the Mtb-infected Mφ was assessed by determining CFU on day 1 and day 4 post-infection. On day 1, WT splenocytes or the NKT cell line were added to the Mtb-infected Mφ, and CFU were determined 72 hrs later on day 4. *, p<0.05, as determined by a one-way ANOVA with Tukey's Multiple Comparison Test. (B) Mtb-infected Mφ were cultured alone or with WT splenocytes or with different numbers of NKT cells as indicated. After 24 hours of coculture, IFN-γ was measured in the culture supernatants by ELISA. (C) After 72 hrs, the cultures from (B) were analyzed for the total CFU and compared to Mtb-infected Mφ alone on day 1 and day 4. All conditions containing splenocytes or iNKT cells had significantly (p<0.05) fewer CFU compared to Mtb-infected Mφ on day 4 post-infection.