Contents -- Introduction -- 1: On the Role of Melanoma-Specific CD8+ T-Cell Immunity in Disease Progression of Advanced-Stage Melanoma Patients. -- 2: Phase I clinical study with multiple peptide vaccines in combination with tetanus toxoid and GM-CSF in advanced-stage HLA-A*0201- positive melanoma patients. -- 3: A rapid and potent DNA vaccination strategy defined by in vivo monitoring of antigen expression -- 4: Superior immunogenicity of DNA tattooing as compared to intramuscular DNA vaccination in non-human primates. -- 5: In vivo antigen stability affects vaccine efficacy -- 6: Intravital imaging of fluorescent markers and FRET probes by DNA tattooing. -- 7: Design and use of conditional MHC class I ligands -- Discussion -- Dutch Summary -- Acknowledgements and Curriculum Vitae.