Elevated IL-7 levels are followed by increased T-cell proliferation and maintenance of stable T-cell numbers in SIVsm-infected mangabeys. Longitudinal assessment of the percentage of proliferating (Ki67⁺) CD4⁺ (dark green, ○) and CD8⁺ T cells (light green, •) in peripheral blood (panels A, C, E, G, I, and K) and plasma IL-7 levels (red, □) are plotted for each individual mangabey (SM1, SM2, SM3, SM4, SM5, and SM6) separately. Absolute numbers of CD4⁺ (turquoise, ▾) and CD8⁺ T cells (blue, ▵) (panels B, D, F, H, J, and L) are given as markers of T-cell homeostasis.