mRNA-based antigen loading of Mo-DCs.

Immature Mo-DCs were cultured with GM-CSF and IL-4 and transfected at day 6 of culture with Melan-A mRNA by electroporation (n = 11), lipofection (n = 8), or passive pulsing (n = 5) or with EGFP mRNA by electroporation (n = 6). The SK23-MEL melanoma cell line, HLA-A2⁺ Mo-DCs pulsed with a Melan-A, or an irrelevant influenza peptide and HLA-A2–negative Mo-DCs electroporated with Melan-A mRNA served as controls. Antigen-presenting cells (indicated on the left of the graph) were coincubated with a Melan-A–specific CD8⁺ CTL clone to determine antigen-loading efficiency, as reflected by IFN-γ production of the CTL clone. Results are shown as mean ± SD. * P < .05; EP, electroporation; lipo, lipofection; puls, passive pulsing.