(A) HLA A*0201 nonamer motif peptide primes matched EBVLCL targets to be lysed by T-cell clone 3-3F4. HLA A*0201 peptides (Table 2) in the region 477-561 AA from HCMV pp65 were synthesized.51,55 62 Matched and mismatched EBVLCL targets were incubated with 10 μmol/L of each peptide or no peptide (none) while ⁵¹Cr loading for 1 hour, the peptide was washed out, and 10,000 of each target was incubated with T-cell clone 3-3F4 at the indicated E:T in a standard CRA. (▤), Matched E:T = 1; (□), matched E:T = 5; (▪), mismatch E:T = 1; (▥), mismatch E:T = 5. (B) Sensitivity of CTL killing to peptide concentration: Comparison of TAP⁺ and TAP⁻ cell lines. T2 (TAP⁻) or JY (TAP⁺) cells were incubated with serial dilutions of pp65_495-503 at the indicated concentration for 1 hour at 37°C. The peptide was washed out and a standard CRA was performed using 10,000 targets at the E:Ts shown. (♦), TAP⁺, E:T = 1; (▪), TAP⁺, E:T = 5; (), TAP⁻, E:T = 1; (×), TAP⁻, E:T = 5.