Lymphocytes from lymph nodes of B6 mice were stimulated with anti-CD3 mAb in the presence of IL-12 (1 ng/ml) or IFN-c (100 ng/ml) in 24-well plates as described above. Supernatants were collected at 48 hr after culture. IL-2 ELISAs were performed using reagents and protocols provided by the manufacturer (eBioscience, Mouse IL-2 ELISA Ready-SET-Go kit). Samples were plated in duplicate.