The 5H10-1 monoclonal antibody specifically recognizes CD8a which is also known as CD8 alpha (CD8α), Ly-2 or Lyt-2. CD8a is an ~34 kDa single pass type I transmembrane glycoprotein that is encoded by Cd8a (CD8 antigen, alpha chain) which belongs to the immunoglobulin superfamily (IgSF). CD8a is comprised of an extracellular region that contains an IgV-like domain followed by a transmembrane region and cytoplasmic tail with a Lck tyrosine kinase binding motif. CD8a is expressed on the cell surface as either a disulfide bond-linked homodimer (CD8αα) or a heterodimer (CD8αβ) when disulfide bonded to CD8b (also known as, CD8 beta/CDβ, Ly-3, or Lyt-3), another type I transmembrane glycoprotein. CD8aβ is expressed on most thymocytes and a subpopulation of mature peripheral TCR αβ T cells including some intraepithelial lymphocytes (IELs). CD8αα is expressed on IELs which include either TCR αβ or TCR γδ T cells as well as on other leucocytes, such as, subsets of NK cells and dendritic cells (DCs). CD8αβ serves as a co-receptor for antigen-stimulated CD8+ T cells by binding to the same peptide:MHC class I complex as the T cell receptor and by helping to trigger the subsequent signaling cascade through Lck activation upon antigen recognition. Through high-affinity binding to nonclassical MHC class-Ib molecules, CD8αα can reportedly function less efficiently as a co-receptor and even repress antigen-stimulated CD8+ T cell responses.
The antibody was conjugated to BD Horizon BV480 which is part of the BD Horizon Brilliant™ Violet family of dyes. With an Ex Max of 436-nm and Em Max at 478-nm, BD Horizon BV480 can be excited by the violet laser and detected in the BD Horizon BV510 (525/40-nm) filter set. BV480 has less spillover into the BV605 detector and, in general, is brighter than BV510.