The median levels of unstimulated IL-15 (IL-15nil) and the IL-15 response to TB antigens (IL-15TB) were significantly lower in those with active TB than the LTBI group (IL-15nil: active TB 94.62 pg/mL, IQR 79.08–109.6 pg/mL; LTBI 162.8 pg/mL, IQR 146.1–222.6 pg/mL, P < 0.001; IL-15TB: active TB 152.2 pg/mL, IQR 114.7–234.6 pg/mL, LTBI 210.4 pg/mL, IQR 177.4–272.4 pg/mL, P = 0.025). Here, IL15 is linked to tuberculosis.