CD33-related siglecs as potential modulators of inflammatory responses

The immune system must be tightly regulated to prevent unwanted tissue damage caused by exaggerated immune and inflammatory reactions. Inhibitory and activating immune receptors play a crucial role in this function via phosphotyrosine-dependent signaling pathways. A significant body of evidence has accumulated suggesting that the siglec family of sialic acid binding Ig-like lectins makes an important contribution to this immunoregulation. The CD33-related siglecs are a distinct subset of inhibitory and activating receptors, expressed primarily on leukocytes in a cell type-specific manner. Here, we critically assess the in vitro and in vivo evidence on the functional role for CD33-related siglecs in modulation of inflammatory and immune responses.