The 1G8 monoclonal antibody specifically recognizes Endothelial cell-selective adhesion molecule (ESAM). ESAM is a ~55 kDa single-pass type I transmembrane glycoprotein that is encoded by ESAM (Endothelial cell-specific adhesion molecule) which belongs to the immunoglobulin supergene superfamily (IgSF). ESAM contains an IgV-type and IgC2-type domain in its extracellular region followed by a transmembrane sequence and cytoplasmic tail. ESAM is strongly expressed on platelets, megakaryocytes, and endothelial cells at interendothelial cell junctions as well as dendritic cells. Through homophilic interactions, this interendothelial cell adhesion molecule may play roles in regulating vascular permeability and in the extravasation of leucocytes, eg, neutrophils, through blood vessel walls. ESAM is also reportedly expressed on hematopoietic stem cells (HSCs). ESAM-positive cell populations are enriched for multipotent myeloid erythroid progenitors and primitive progenitors with lymphopoietic activity.
The antibody was conjugated to BD Horizon™ BUV563 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 which has an Ex Max of 348 nm and an acceptor dye. The tandem has an Em Max at 563 nm. BD Horizon BUV563 can be excited by the 355 nm ultraviolet laser. On instruments with a 561 nm Yellow-Green laser, the recommended bandpass filter is 585/15 nm with a 535 nm long pass to minimize laser light leakage. When BD Horizon BUV563 is used with an instrument that does not have a 561 nm laser, a 560/40 nm filter with a 535 nm long pass may be more optimal. Due to the excitation and emission characteristics of the acceptor dye, there may be spillover into the PE and PE-CF594 detectors. However, the spillover can be corrected through compensation as with any other dye combination.