Photoconverted cells allow rapid assessment of vaccine adjuvant potency in mice.

Identifying vaccine adjuvants that optimally enhance CD8+ T cell responses remain a challenge, often requiring time-consuming and resource-intensive methods. Here, we introduce a photoconversion-based approach using KikGR mice to track migratory dendritic cells (Mig DCs) within 48 h post-vaccination. This method enables real-time visualization of skin-derived Mig DCs migration to draining lymph nodes (dLNs), providing an early and reliable predictor of CD8+ T cell priming and anti-tumor efficacy. Unlike traditional techniques that demand extensive experimentation, this system allows for faster, cost-effective screening of adjuvants. We further demonstrate that blocking CCR7 significantly reduces Mig DCs migration, impairing CD8+ T cell responses. Our approach revolutionizes adjuvant evaluation, enabling swift and accurate immune assessments, particularly in therapeutic vaccine development.