Target cell reactivity of HA-1– and HA-2–specific ex vivo–induced CTLs using various types of APCs pulsed with synthetic peptides. The type of APC used to induce CTLs is indicated on the x-axis. Below the x-axis, the number of CTLs generated using the same type of APC (but in all cases from a different individual) and the total number of attempts are indicated. Effector-to-target ratio was 20:1.