The 20d5 monoclonal antibody specifically recognizes NKG2A, NKG2C, and NKG2E (also known as CD159a, CD159c, and CD159e which are encoded by Klrc1, Klrc2, and Klrc3, respectively) on a subset of NK and NK-T cells in most strains tested (eg, AKR/J, BALB/c, C3H/He, C57BL/6, CBA/J, DBA/1, FVB/N, 129/Sv, NOD, SWR, and most DBA/2 substrains, but not DBA/2J). The NKG2 molecules are a family of lectin-like receptors that form heterodimers with CD94 on the surface of NK cells. DBA/2J mice do not express CD94, and the lack of CD94 is responsible for the absence of NKG2 expression in this substrain. NKG2 receptors are also expressed on CD8+ T lymphocytes activated in vivo and in vitro. The heterodimers of CD94 with NKG2A, C, or E recognize Qa-1, a nonclassical MHC class I antigen, presenting the Qdm peptide. Studies of CD94/NKG2 heterodimers on human NK cells have demonstrated that the NKG2 components mediate signal transduction for the receptor, with NKG2A being inhibitory and NKG2C being stimulatory. The CD94/NKG2E heterodimer is also thought to be stimulatory. The mouse NKG2A molecule contains two intracytoplasmic sequences that resemble the ITIM (Immunoreceptor Tyrosine- based Inhibitory Motif) consensus sequence. NKG2A transcripts have been shown to be up to 20-fold more abundant than NKG2C and NKG2E mRNA in NK cells of adult mice. The CD94/NKG2 receptors show increased expression on neonatal NK cells compared to the Ly-49 MHC class I receptors, suggesting that CD94/NKG2 receptors and their ligand, Qa-1, may play a role in maintenance of self-tolerance in developing NK cells. The 20d5 antibody is useful for identification of NK cells expressing functional CD94/NKG2 receptors, in contrast to the non-functional CD94 expressed alone, and it blocks the binding of Qdm-complexed Qa-1b tetramers to CD94/NKG2-transfected CHO cells.
The antibody was conjugated to BD Horizon™ BB700, which is part of the BD Horizon Brilliant™ Blue family of dyes. It is a polymer-based tandem dye developed exclusively by BD Biosciences. With an excitation max of 485 nm and an emission max of 693 nm, BD Horizon BB700 can be excited by the 488 nm laser and detected in a standard PerCP-Cy™5.5 set (eg, 695/40-nm filter). This dye provides a much brighter alternative to PerCP-Cy5.5 with less cross laser excitation off the 405 nm and 355 nm lasers.