Figure 2. Antigen-specific immune response in the lungs and spleens of mice primarily vaccinated with exosomes containing mycobacterial proteins.

(A–D) Flow cytometric analysis of antigen-specific cytokine – expressing CD4⁺ and CD8⁺ T cells isolated from the spleens and lungs of vaccinated or non-vaccinated mice. The frequency of INF-γ-positive CD4⁺ (A) or CD8⁺ (B) T cells as well as the frequency of IL-2 positive CD4⁺ (C) or CD8⁺ (D) T cells after ex vivo stimulation with M. tuberculosis antigens. (E and F) IFN-γ and IL-2 ELISA using spleen and lung cells isolated from vaccinated and non-vaccinated mice. The results are expressed as the cytokine concentration after ex vivo stimulation of 1×10⁶ cells with M. tuberculosis antigens. The data shown +/− standard error of pooled lung or spleen homogenate from 5 mice per given condition run in duplicate and is the representative of three independent experiments. *, p < 0.05 compared to PBS control (one-way ANOVA with Tukey post-test. UT20 and UT40, exosomes (20 or 40µg) isolated from untreated marcophages; CFP20 and CFP40, exosomes (20 or 40µg) isolated from macrophages pulsed with M. tuberculosis CFP.