Figure 1.

CD27L/CD70 signaling is essential for CTL induction. T lymphocytes (10⁶) were incubated with various numbers of paraformaldehyde-fixed CD70 Tx, CD27 Tx, or mock Tx and autologous DC (10⁴) presenting HIV-RT peptides for CTL and PADRE helper epitopes. After 9 days, induction of specific cytolytic activity was determined by the ability of cultured cells to lyse 5,000 ⁵¹Cr-labeled T2 target cells coated with HIV-RT epitopes (A) or irrelevant GP2 peptides (B). (C) Metrizamide-enriched DC (3 × 10⁴) were pulsed with HIV and PADRE peptides and cultured with CTL (5 × 10⁵) and CD45RO⁺ Th (5 × 10⁵), CD45RA⁺ Th (5 × 10⁵), or without Th cells in the presence of various numbers of fixed CD27 Tx, CD70 Tx, or mock Tx. After 9 days, specific lysis of HIV peptide-coated T2 cells was determined as described. Specific lysis of T2-targets expressing an irrelevant antigen was <15% in this culture. Data are representative for five independent assays. Standard deviations were <15% of the values shown.