Figure 4.

CD8⁺ T cell activation induced by M. tuberculosis–infected Alox5^−/− macrophages requires cross-presentation by CD11c⁺ DCs. (a,b) CD8⁺ T cell proliferation (a) and population expansion of cells positive for the H-2K^b–SIINFEKL pentamer (b) 5 d after intravenous transfer of CFSE-labeled Thy-1.2⁺ splenic OT-I CD8⁺ T cells into Thy-1.1⁺ B6.PL mice, followed within 24 h by M. tuberculosis H37Rv–infected wild-type or Alox5^−/− macrophages pulsed with SIINFEKL. Numbers above bracketed lines (a) indicate percent CFSE⁻ cells (left) or CFSE⁺ cells (right); numbers adjacent to outlined areas (b) indicate percent CD8⁺ T cells stained with H-2K^b–SIINFEKL. (c) Frequency of SIINFEKL-specific CD8⁺ T cells in the draining lymph nodes of CD11c-DTR–transgenic mice (CD11c-DTR) and nontransgenic littermate control mice (Non-TG) given intravenous injection of OT-I CD8⁺ T cells, followed by subcutaneous transfer of M. tuberculosis H37Rv–infected, SIINFEKL-pulsed Alox5^−/− macrophages and treatment with diphtheria toxin. No Mϕ (right), control mice that did not receive macrophages. Numbers adjacent to outlined areas indicate percent CD8⁺ T cells stained with H-2K^b–SIINFEKL after 5 d. Data are representative of three experiments (mean and s.e.m. of four to five mice per group). (d) OVA-specific OT-I CD8⁺ T cells in draining lymph nodes of β₂-microglobulin-deficient (B2m^−/−), TAP-1-deficient (Tap1^−/−) or Thy-1.1⁺ recipient mice 5 d after the transfer of CFSE-labeled Thy-1.2⁺ splenic OT-I CD8⁺ T cells and M. tuberculosis H37Rv–infected, SIINFEKL-pulsed wild-type or Alox5^−/− macrophages. Data are representative of two to three independent experiments (mean ± s.e.m. of three to five mice per group). *P < 0.05 (one-way ANOVA).