Antigenic stimulation makes anergic T-HA cells responsive to nonmitogenic concentrations of growth factors.

IL-15-conditioned T-HA cells were stimulated for 48 hours with immobilized anti-CD3 mAb (first stimulus), recovered, and further cultured for 12 days with IL-2 (10 ng/mL) or IL-15 (1 ng/mL) (intermittent culture). On day 14, 1 × 10⁴ of these anergic T-HA cells were restimulated with medium (open bars), APC (middle bars), or antigen/APC (solid bars) in the absence or presence of IL-2 (1 ng/mL) or IL-15 (1 ng/mL) (restimulation). Proliferation was measured by addition of [³H]thymidine for the last 12 hours of the 72-hour assay period. Data shown are mean cpm from triplicate cultures ± SD. This experiment was performed 3 times with comparable results.