58 T cells transduced with different formats of P14 and OT-I TCRs. 58 T cells were retrovirally transduced with different formats of the P14 (A) and OT-I TCR (B) and tested for their functionality by cocultivation with 8 × 104 peptide-loaded splenocytes. TCR expression was measured by CD3 (18–33%) and adjusted to 8 × 104 TCR-positive cells per well. Murine IL-2 was determined in the supernatant 24 h later by ELISA. Bars indicate mean ± SD of two T cell samples each measured twice for IL-2 secretion (n = 4) after cocultivation.