IL-15-conditioned T-HA cells were stimulated for 48 hours with immobilized anti-CD3 mAb or Ag/APC (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, 5 × 10⁴ of these anergic and nonanergic T-HA cells were restimulated with APC or Ag/APC (second stimulus). After 24 hours, supernatants were taken and analyzed for IFN-γ and GM-CSF content. This experiment was performed 3 times with comparable results. APC indicates, antigen-presenting cell; Ag, antigen; GM-CSF, granulocyte/macrophage colony-stimulating factor; IFN, interferon; IL, interleukin; mAb, monoclonal antibody.