The TU66 monoclonal antibody specifically recognizes human CD39 which is also known as Ectonucleoside triphosphate diphosphohydrolase 1 (NTPDase 1), Ecto-ATP diphosphohydrolase 1 (Ecto-ATPDase 1), or Ecto-apyrase. CD39 is an integral membrane glycoprotein with two transmembrane domains, N- and C-terminal cytoplasmic tails, and an extracellular region that contains the NTPDase 1 active site. CD39 is encoded by ENTPD1 which belongs to the ectoenzyme family. CD39 is variably expressed on activated T cells and B cells, regulatory T cells (Treg), dendritic cells, Langerhans cells, NK cells, monocytes, macrophages, endothelial cells, and granulocytes. CD39 acts on extracellular nucleoside triphosphates and diphosphates including ATP and ADP that are hydrolyzed into AMP. Through cell surface CD73 (Ecto-5'-nucleotidase), regulatory T cells can act on extracellular AMP to generate immunosuppressive adenosine. CD39 is involved in the control of the extracellular pool of phosphorylated nucleosides, the suppression of inflammation and immunity, and the regulation of platelet activation.
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.