Laminarin-mediated targeting to Dectin-1 enhances antigen-specific immune responses

It has immense potential for immunotherapy and vaccination to target antigens to antigen-presenting cells (APCs). Here we described a method for delivering whole protein antigens to APCs via carbohydrate-mediated targeting of Dectin-1, which is a C-type lectin and mainly expresses on subpopulations of dendritic cells and macrophages. Laminarin, which is a beta-1-3 glucan and a typical ligand for Dectin-1, was chemically coupled to ovalbumin (OVA). Compared to OVA alone, the conjugate was effectively recognized and ingested by CHO cells stably expressing Dectin-1 and bound to bone marrow dendritic cells (BMDCs) via Dectin-1. Laminarin modification led to significant enhancement of OVA-specific CD4(+) T-cell response. Moreover, when used to immunize mice, the conjugate enhanced the primary IgG antibody response to OVA. Taken together, our data suggest that APCs targeting based on glucan-Dectin-1 interaction is a promising approach to improve vaccines.