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 BV421 which is part of the BD Horizon Brilliant™ Violet family of dyes. With an Ex Max near 407 nm and Em Max near 421 nm, BD Horizon BV421 can be excited by the violet laser (405 nm) and detected with a 450/50 nm filter. BD Horizon BV421 conjugates are very bright, often exhibiting a 10 fold improvement in brightness compared to Pacific Blue™ conjugates. Due to nearly identical excitation and emission properties but different spillover characteristics, BD Horizon BV421, Pacific Blue™, and BD Horizon V450 cannot be used simultaneously.