CLEC4A, also known as lectin-like immunoreceptor (LLIR) and dendritic cell immunoreceptor (DCIR), is a type II transmembrane protein belonging to C-type lectin domain family, and was previously designated as CLECSF6. It contains one carbohydrate recognition domain in its C-terminal extracellular domain and an immunoreceptor tyrosine-based inhibitory motif (ITIM) in its cytoplasmic domain. CLEC4A is mainly expressed on monocytes, macrophages, dendritic cells, neutrophils, and B cells. It is also found on the surface of CD4+ T cells in rheumatoid arthritis (RA) patients. CLEC4A has been reported to function as a receptor for HIV, cross-present and cross-prime human CD8+ T cells. It might also function as a negative player by recruiting the SHP-1 or/and SHP-2 phosphotase through its immunoreceptor tyrosine-based inhibitory motif (ITIM).