Siglecs, sialic acids and innate immunity

Siglecs are members of the Ig superfamily that bind to sialic acid (Sia) an d are mainly expressed by cells of the hematopoietic system. Until three ye ars ago, only four Siglecs were known, namely sialoadhesin. CD22, myelin-as sociated glycoprotein and CD33. Since then, a further six human CD33-relate d Siglecs with features of inhibitory receptors have been identified and sh own to be expressed by discrete subsets of leukocytes. Recognition of Sia b y these Siglecs could play a role in the regulation of the innate immune sy stem.