The 7E.17G9 monoclonal antibody specifically binds to CD278, the Inducible Costimulatory molecule (ICOS), a 47-57 kDa homodimeric glycoprotein of the CD28 family of costimulatory molecules. ICOS is expressed on subpopulations of CD4-CD8- and CD4+CD8- (but not CD4-CD8+ or CD4+CD8+) thymocytes, on some T-cell lines, and on small numbers of peripheral leukocytes. It is upregulated on T lymphocytes following activation via the T-cell receptor. The T-cell activation marker H4 is the same molecule as ICOS. ICOS is a costimulatory receptor, and its ligand on antigen-presenting cells has been called B7RP-1, GL50, B7h, B7-H2, or LICOS. There is considerable evidence that the interaction of ICOS with its ligand is involved in the regulation of many, but not all, T-cell-mediated immune responses.
The antibody was conjugated to BD Horizon™ BV711 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 711-nm. BD Horizon BV711 can be excited by the violet laser and detected in a filter used to detect Cy™5.5 / Alexa Fluor® 700-like dyes (eg, 712/20-nm filter). Due to the excitation and emission characteristics of the acceptor dye, there may be moderate spillover into the Alexa Fluor® 700 and PerCP-Cy5.5 detectors. However, the spillover can be corrected through compensation as with any other dye combination.