Glycan modification of antigen alters its intracellular routing in dendritic cells, promoting priming of T cells.

Antigen uptake by dendritic cells and intracellular routing of antigens to specific compartments is regulated by C-type lectin receptors that recognize glycan structures. We show that the modification of Ovalbumin (OVA) with the glycan-structure Lewis(X) (Le(X)) re-directs OVA to the C-type lectin receptor MGL1. Le(X)-modification of OVA favored Th1 skewing of CD4(+) T cells and enhanced cross-priming of CD8(+) T cells. While cross-presentation of native OVA requires high antigen dose and TLR stimuli, Le(X) modification reduces the required amount 100-fold and obviates its dependence on TLR signaling. The OVA-Le(X)-induced enhancement of T cell cross-priming is MGL1-dependent as shown by reduced CD8(+) effector T cell frequencies in MGL1-deficient mice. Moreover, MGL1-mediated cross-presentation of OVA-Le(X) neither required TAP-transporters nor Cathepsin-S and was still observed after prolonged intracellular storage of antigen in Rab11(+)LAMP1(+) compartments. We conclude that controlled neo-glycosylation of antigens can crucially influence intracellular routing of antigens, the nature and strength of immune responses and should be considered for optimizing current vaccination strategies.