Binding activities of non-β-glucan glycoclusters to dectin-1 and exploration of their binding site.

Dectin-1, which specifically recognizes β-(1,3)-glucans, plays an important role in innate immune responses. For the first time, in this study we found that a series of non-β-glucan glycoclusters can bind to dectin-1 by means of surface plasmon resonance (SPR) assay. Hexavalent lactoside Ju-6 showed the strongest affinity property (KD=1.6 µM). Interestingly, a continuous binding-dissociation experiment on SPR showed that Ju-6 and Laminarin binding to dectin-1 are independent of each other. Moreover, RT-PCR assay showed that Ju-6 cannot up-regulate cytokine gene expression or inhibit the promoting effect caused by Zymosan (a long-chain β-glucan). These results indicated that there might be a possible new carbohydrate binding site on dectin-1.