Figure 3.

Presence of antagonist APL prevents induction of complete protein tyrosine phosphorylation profile in response to agonist peptide. (a) CTL (10⁶) from the HLA A2-restricted line recognizing HIV-1 p17-8 Gag were presented for different times (2, 10, 20, 40, or 80 min) with 10⁵ APC either presenting agonist peptide alone or copresenting agonist peptide (SLYNTVATL) and antagonistic APL (3F, 5A). To present peptide, APC were pulsed with 1 nM agonist peptide for 2 hr, washed with RPMI medium 1640, and then either pulsed for a further 2 hr with 1 nM APL (for copresentation) or resuspended in the absence of peptide for 2 hr (for agonist presentation alone). Cell lysates were electrophoresed and immunoblotted with anti-phosphotyrosine mAb. The disappearance of the ζ₂ chain observed at 2 and 10 min during agonist and APL copresentation was not observed in subsequent experiments, and is most likely an artifact of Western blotting. Data are representative of at least four experiments. (b) As in a, except that peptides were used at 1 μM. Data are representative of at least four experiments.