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™ BUV496 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 with an Ex Max of 348-nm and an acceptor dye with an Em Max at 496-nm. BD Horizon BUV496 can be excited by the ultraviolet laser (355 nm) and detected with a 515/30 nm filter with a 450LP. Due to the excitation of the acceptor dye by other laser lines, there may be significant spillover into the channel detecting BD Horizon V500 or BV510 (eg, 525/40-nm filter). However, the spillover can be corrected through compensation as with any other dye combination.