The monoclonal antibody specifically recognizes CD33, a human myelomonocytic antigen which is also known as Sialic acid-binding Ig-like lectin 3 (Siglec-3 or SIGLEC3). CD33 is a 67 kDa type I transmembrane glycoprotein that belongs to the Ig supergene family. The CD33 antigen is present on monocytes (bright) and granulocytes (dim). Granulocytes can be further subdivided into neutrophil, eosinophil, and basophil populations based on CD33 staining in combination with other cell-surface antigens. The CD33 antigen is also found on CFU-Mix, CFU-GM, CFU-Meg, a portion of BFU-E, myeloblasts, promyelocytes, myelocytes, and metamyelocytes, but not on earlier precursors. The CD33 antigen is expressed on blast cells in greater than 85% of acute myeloid leukemias (AML), and it can be aberrantly expressed in acute lymphoblastic leukemias (ALL). Normal lymphocytes, platelets, and erythrocytes do not express the CD33 antigen. CD33 can reportedly function as a sialic acid-dependent cell adhesion molecule and this function can be modulated by endogenous sialoglycoconjugates when CD33 is expressed on the membrane.
The antibody was conjugated to BD Horizon BUV615 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome with an Ex Max near 350 nm and an Em Max near 615 nm. BD Horizon Brilliant BUV615 can be excited by the ultraviolet laser (355 nm) and detected with a 610/20 filter and a 595 nm LP. Due to the excitation of the acceptor dye by the blue/yellow-green laser line, there may be significant spillover into channels detecting PE-CF594 like emissions (eg, 610/20-nm filter).