The DX29 monoclonal antibody specifically binds to human CD278, which is also known as Inducible Costimulator (ICOS) or Inducible T-cell Costimulator. ICOS is a homodimeric type I transmembrane glycoprotein with an approximate molecular weight of 50-60 kDa. It is a member of the CD28 family and is highly expressed on activated T cells. CD278 is the receptor for ICOS-ligand (also known as, CD275, B7-H2, B7RP-1, or LICOS). Like CD28, ICOS can provide a costimulatory signal for T cell activation, proliferation and cytokine production. It is not expressed on resting or activated B cells, monocytes, NK cells, granulocytes, dendritic cells or platelets. Unlike the constitutively expressed CD28, ICOS is de novo expressed upon cellular activation. Reports describe similarities between CD28 and ICOS in T cell activation, such as the costimulation of cytokine production. However, it has been suggested that ICOS may play a greater role in IL-10 production. In the presence of IL-10, purified recombinant human ICOS protein significantly increased in vitro B cell growth stimulated by pokeweed mitogen (PWM) and enhanced production of IgG.
The antibody was conjugated to an oligonucleotide that contains an antibody clone-specific barcode (ABC) flanked by a poly-A tail on the 3' end and a PCR handle (PCR primer binding site) on the 5' end. The ABC for this antibody was designed to be used with other BD AbSeq oligonucleotides conjugated to other antibodies. All AbSeq ABC sequences were selected in silico to be unique from human and mouse genomes, have low predicted secondary structure, and have high Hamming distance within the BD AbSeq portfolio, to allow for sequencing error correction and unique mapping. The poly-A tail of the oligonucleotide allows the ABC to be captured by the BD Rhapsody™ system or other oligo-dT-based capture systems. The 5' PCR handle allows for efficient sequencing library generation for Illumina sequencing platforms.