5IHB, 5J06, 5J0B, 6D48, 6D49, 6D4A, 6TL8, 7AW694512489ENSG00000105383ENSMUSG00000004609P20138Q63994NM_001082618NM_001177608NM_001772NM_001111058NM_021293NP_001076087NP_001171079NP_001763NP_001104528NP_067268CD33 or Siglec-3 (sialic acid binding Ig-like lectin 3, SIGLEC3, SIGLEC-3, gp67, p67) is a transmembrane receptor expressed on cells of myeloid lineage.

The intracellular portion of CD33 contains immunoreceptor tyrosine-based inhibitory motifs (ITIMs) that are implicated in inhibition of cellular activity.

[8] CD33 controls microglial activation but in Alzheimer disease it goes overdrive in presence of amyloid and tau proteins, its expression is known to be tied to TREM2.

[9][10][11][12] CD33 is the target of gemtuzumab ozogamicin (trade name: Mylotarg®; Pfizer/Wyeth-Ayerst Laboratories),[13] an antibody-drug conjugate (ADC) for the treatment of patients with acute myeloid leukemia.

[17][18][19] CD33 is also the target in Vadastuximab talirine (SGN-CD33A), a novel antibody-drug conjugate being developed by Seattle Genetics, utilizing this company's ADC technology.