Sialic acid-binding immunoglobulin-like lectin 3 (CD33 (Siglec-3))

Sialic acid-binding immunoglobulin-like lectin 3 (CD33 or Siglec-3) is a cell surface receptor predominantly expressed on myeloid progenitor cells, monocytes, macrophages, and microglia[2][6]. As a member of the Siglec family within the immunoglobulin superfamily, it binds sialic acid residues via its N-terminal V-set Ig-like domain and plays a critical inhibitory role in immune cell signaling by ITIM motifs in its cytoplasmic tail[1][3][4]. CD33 is a key checkpoint molecule and a therapeutic target in acute myeloid leukemia, where it is engaged by monoclonal antibodies and CAR-T cells to direct cytotoxic activity against malignant cells[2]. Its expression on normal hematopoietic cells presents therapeutic challenges due to potential on-target cytopenias, and careful patient selection based on CD33 expression is required[2].

Other names

CD33Siglec-3GP67SIGLEC3sialic acid-binding immunoglobulin-like lectin 3

Monoclonal antibodies and antibody-drug conjugates: Bind to CD33 on leukemic cells, deliver cytotoxic drugs, or mediate immune clearance CAR-T cells: Genetically engineered to target CD33, leading to direct cytotoxicity Inhibiting CD33 signaling can enhance immune responses against cancer cells