Expansion of CTLs. In vitro expansion of purified HA-1–specific CD8⁺ CTLs of D1 (left) and D2 (right) by HD-aAPCs (♦) and by LD-aAPCs (⋄). The number of days given refers to the days of expansion after the first sort. Cell numbers after first sort were 6.3 × 10³ HD-aAPC– and 1.07 × 10⁴ LD-aAPC–induced CTLs for D1 and 6.2 × 10⁴ HD-aAPC– and 1.3 × 10⁴ LD-aAPC–induced CTLs for D2.