FIG. 6.

Intracellular cytokine staining (IFN-γ and TNF-α) of LCMV-specific CD8⁺ T cells indicates that transfection of H-2^d BALB cells with ubiquitinated Traub NP aa 116 to 140 leads to activation of significantly less CD8⁺ T cells than does activation by ubiquitinated ARM NP aa 116 to 140 (P value for IFN-γ expression, 0.0003; P value for TNF-α expression, 0.0027). However, when either peptide is externally added to coat target cells (Traub and ARM NP aa 116 to 131), equivalent numbers of cytokine-containing CD8⁺ T cells (i.e., 43 and 42% IFN-γ-expressing CD8⁺ T cells, respectively) are generated. The data are representative of three independent experiments.