The 2D9 monoclonal antibody recognizes C57BL/6 mouse Natural killer cell receptor P1D (NKR-P1D) which is also known as NKR-P1B[B6], or CD161b. CD161b is encoded by Klrb1b (killer cell lectin-like receptor subfamily B member 1B). CD161b is expressed by a functionally distinct subset of natural killer (NK) cells that express higher levels of cytotoxicity and interferon-γ (IFN-γ) than their CD161b-low or -negative counterparts. CD161b is a type II transmembrane glycoprotein that contains an immunoreceptor tyrosine-based inhibitory motif in its cytoplasmic domain. CD161b binds to C-type lectin related protein b (Clr-b) and may play a role in regulating NK cell responses. The 2D9 antibody has slight crossreactivity with cells transfected with Klrb1a/NKRP1A, Klrb1c/NKRP1C, or Klrb1f/NKRP1F.
The antibody was conjugated to BD Horizon™ BV650 which is part of the BD Horizon Brilliant™ Violet family of dyes. This dye is a tandem fluorochrome of BD Horizon BV421 with an Ex Max of 405-nm and an acceptor dye with an Em Max at 650-nm. BD Horizon BV650 can be excited by the violet laser and detected in a filter used to detect APC-like dyes (eg, 660/20-nm filter). Due to the excitation and emission characteristics of the acceptor dye, there will be spillover into the APC and Alexa Fluor® 700 detectors. However, the spillover can be corrected through compensation as with any other dye combination.