Functional Specialty of CD40 and Dendritic Cell Surface Lectins for Exogenous Antigen Presentation to CD8 ⁺ and CD4 ⁺ T Cells

Dendritic cells (DCs) are major antigen-presenting cells that can efficiently prime and cross-prime antigen-specific T cells. Delivering antigen to DCs via surface receptors is thus an appealing strategy to evoke cellular immunity. Nonetheless, which DC surface receptor to target to yield the optimal CD8 ⁺ and CD4 ⁺ T cell responses remains elusive. Herein, we report the superiority of CD40 over 9 different lectins and scavenger receptors at evoking antigen-specific CD8 ⁺ T cell responses. However, lectins (e.g., LOX-1 and Dectin-1) were more efficient than CD40 at eliciting CD4 ⁺ T cell responses. Common and distinct patterns of subcellular and intracellular localization of receptor-bound αCD40, αLOX-1 and αDectin-1 further support their functional specialization at enhancing antigen presentation to either CD8 ⁺ or CD4 ⁺ T cells. Lastly, we demonstrate that antigen targeting to CD40 can evoke potent antigen-specific CD8 ⁺ T cell responses in human CD40 transgenic mice. This study provides fundamental information for the rational design of vaccines against cancers and viral infections.