IFN-γ⁺ memory cells co-produce IL-21, and <i>Ifng</i>-accessibility and T-bet are maintained by division during chronic malaria infection.

<p>(A) BAC-In mice (CD45.2) were infected and at day 7 post-infection, CD4⁺ <i>Ifng</i>/<i>Thy1</i>.<i>1</i>⁺ T cells were purified, CTV labeled, and adoptively transferred into infection-matched CD45.1 recipients. At day 60 post-infection, splenocytes were analyzed by flow cytometry. (B) Dot plot and bar graph shows expression of <i>Ifng/Thy1</i>.<i>1</i> in recovered donor cells. (C) Contour plots gated on CD4⁺CD45.2⁺ show expression of CXCR3 and T-bet in recovered <i>Ifng</i>/<i>Thy1</i>.<i>1</i>⁺ and <i>Ifng</i>/<i>Thy1</i>.<i>1</i>^- populations. Bar graph shows T-bet MFI. (D) <i>Ifng</i>/<i>Thy1</i>.<i>1</i> and T-bet within the CTV^- maximally divided cells. Bar graph shows T-bet MFI in each division (E) IFN-γ and IL-21 expression <i>ex vivo</i> in CD4⁺CD45.2⁺ donor cells. Data are representative of two independent experiments with 3–4 mice per experiment. Statistical significance shown using Students <i>t</i>-test. Error bars represent SEM; ^★<i>p</i> < 0.05, ^★★★<i>p</i> < 0.001.