CD22

CD22 or cluster of differentiation-22, is a molecule belonging to the SIGLEC family of lectins. Generally speaking, CD22 is a regulatory molecule that prevents the overactivation of the immune system and the development of autoimmune diseases.

CD22 is a sugar binding transmembrane protein, which specifically binds sialic acid with an immunoglobulin (Ig) domain located at its N-terminus. The presence of Ig domains makes CD22 a member of the immunoglobulin superfamily. CD22 functions as an inhibitory receptor for B cell receptor (BCR) signalling.

EBV (Ebstein Bar Virus) is known to bind to the B lymphocyte via the CD22 receptor.

An immunotoxin, BL22, that targets this receptor is being tested at the NIH.