Dendritic Cell Lectin （DLEC）, also known as BDCA-2, CD303, HECL, and alternatively designated as CLEC4C/CLECSF11/CLECSF7, is a 38 kDa type II transmembrane protein belonging to the C-type lectin family. DLEC is selectively expressed in plasmacytoid dendritic cells （pDCs） and its expression is downregulated as these cells mature.
pDCs are integral to the innate immune response, particularly in the production of IFN-alpha/beta upon exposure to Toll-like receptor （TLR） 7 and TLR9 agonists, such as microbial CpG DNA. The ligation of DLEC on pDCs with specific antibodies has been shown to attenuate the CpG-stimulated production of interferons and to modulate the Th1 response. Monoclonal antibodies targeting CLEC4C have demonstrated efficacy in achieving disease control in patients with cutaneous lupus erythematosus.
The suppression of IFN-alpha production mediated by CLEC4C is regulated through the masking and unmasking of galactose moieties on the protein. This mechanism represents a novel potential strategy for modulating immune responses in various pathological conditions.