Anti-CD33 Antibody, mAb

CD33, also known as Siglec-3, is a transmembrane protein belonging to the sialic acid-binding immunoglobulin-like lectin (Siglec) family. It possesses both protein phosphatase-binding activity and sialic acid-binding capability, enabling it to participate in key regulatory processes such as the negative regulation of cytokine production, suppression of monocyte activation, and positive regulation of protein tyrosine phosphatase activity.

Localized in multiple cellular compartments including the Golgi apparatus, the outer leaflet of the plasma membrane, and peroxisomes, CD33 functions as an inhibitory receptor that modulates immune cell signaling. It is primarily expressed on myeloid lineage cells, including monocytes, macrophages, and granulocytes, and has gained significant clinical attention as a cell surface marker for acute myeloid leukemia (AML).

Due to its restricted expression on malignant myeloid cells, CD33 has emerged as a critical therapeutic target in AML. Gemtuzumab ozogamicin, an antibody-drug conjugate targeting CD33, has been approved for the treatment of relapsed or refractory AML, underscoring its translational importance in hematologic oncology. Research continues to explore its role in immune regulation and its potential as a target for novel immunotherapeutic strategies.