Selection of DNA aptamers against DC-SIGN protein.

Dendritic cells (DCs) are professional antigen-presenting cells and have come to be appreciated as critical controllers of the immune response, especially T cell responses. Apart from presenting antigens to T cells, DCs carry out many other functions in regulating immunity. DC-specific intercellular adhesion molecule (ICAM)-3 grabbing non-integrin (DC-SIGN) is a novel receptor that plays an important role in DC migration and adhesion, the inflammatory response, T cell activation, initiating the immune response, and immune escape of pathogens and tumors. DC-SIGN mediates DC binding to ICAM-3 on the T cell surface and ICAM-2 on the endothelial cell (EC) surface, and takes part in the initial interaction between DC and T cells or vascular ECs. The procedure of systematic evolution of ligands by exponential enrichment (SELEX) is a method in which single-stranded oligonucleotides are selected from a wide variety of sequences, based on their interaction with a target molecule. In this study, we selected DNA aptamers against DC-SIGN protein by SELEX, and measured their binding affinity for DC-SIGN. Finally, an appropriate aptamer with high affinity for DC-SIGN was obtained, and it blocked DC adhesion to ECs as effectively as anti-DC-SIGN monoclonal antibody.