This study investigates the factors influencing the migration of dendritic cells (DCs) to draining lymph nodes and their impact on T cell priming. The research shows that the efficiency of DC migration varies with the number of injected DCs and that CCR7+/+ DCs, which can migrate to the lymph node, efficiently induce an increase in lymph node cellularity before T cell proliferation. Preinjection of inflammatory cytokines, such as TNF, can enhance DC migration by increasing the expression of CCL21, a chemokine that attracts CCR7+ DCs. The magnitude and quality of the CD4+ T cell response are proportional to the number of antigen-carrying DCs reaching the lymph node and can be significantly boosted by preinjection of TNF. These findings highlight the importance of DC number and tissue inflammation in DC-based vaccination. The study also reveals that DC migration can be enhanced by inflammatory stimuli through up-regulation of CCL21 on lymphatic endothelial cells, suggesting that tissue conditioning can improve T cell responses. Overall, the results emphasize the critical role of DC migration and tissue inflammation in optimizing T cell priming and vaccine efficacy.This study investigates the factors influencing the migration of dendritic cells (DCs) to draining lymph nodes and their impact on T cell priming. The research shows that the efficiency of DC migration varies with the number of injected DCs and that CCR7+/+ DCs, which can migrate to the lymph node, efficiently induce an increase in lymph node cellularity before T cell proliferation. Preinjection of inflammatory cytokines, such as TNF, can enhance DC migration by increasing the expression of CCL21, a chemokine that attracts CCR7+ DCs. The magnitude and quality of the CD4+ T cell response are proportional to the number of antigen-carrying DCs reaching the lymph node and can be significantly boosted by preinjection of TNF. These findings highlight the importance of DC number and tissue inflammation in DC-based vaccination. The study also reveals that DC migration can be enhanced by inflammatory stimuli through up-regulation of CCL21 on lymphatic endothelial cells, suggesting that tissue conditioning can improve T cell responses. Overall, the results emphasize the critical role of DC migration and tissue inflammation in optimizing T cell priming and vaccine efficacy.