Proliferative activity of T cells retrieved from the lung of patients with HIV infection after stimulation with IL-2, IL-15, and TNF-α and with different combinations of the above cytokines. BAL T cells proliferated in the presence of IL-15 or IL-2, but not TNF-α alone. The concurrent stimulation with IL-2 (100 IU/mL) and TNF-α (100 IU/mL) significantly increases the IL-15–mediated T-cell proliferation.