The SK9 monoclonal antibody specifically recognizes CD1a. CD1a is a ~49 kDa type I transmembrane glycoprotein that associates non-covalently with β2-microglobulin. The CD1a antigen is present on 60% to 90% of thymocytes, some T-cell leukemias and lymphomas, Langerhans cells, and a subset of dendritic cells. The CD1a antibody does not react with peripheral blood T and B lymphocytes, monocytes, normal bone marrow mononuclear cells, or normal tonsillar B and T lymphocytes. The CD1a antigen has structural similarities to MHC class I antigens and plays a role in the presentation of non-peptide antigens.
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.