The BRIC 203 monoclonal antibody specifically binds to the Kell blood group antigen, Kp(a-b+) but not Kp(a+b-), also known as the Kell blood group metallo-endopeptidase, KELL, ECE3 and CD238. CD238 is an approximately 115-kDa type II transmembrane glycoprotein that is encoded by the KEL gene. CD238 functions as a zinc endopeptidase that cleaves endothelin-3 into an active form which can function as a vasoconstrictor. CD238 is expressed on erythrocytes, human embryonic stem cell-derived endoderm and on cells from various other tissues, including testis, heart, brain and skeletal muscle. Decreased expression of CD238 is associated with the McLeod phenotype as a consequence of losing XK protein expression. Kell antigen expression can play an important role during blood transfusions and also specific autoimmune diseases related to Kell antigen recognition. During development the BRIC 203 monoclonal antibody was found to detect the CD238 antigen by flow cytometric analysis of human erythrocytes. It reportedly works in immunoprecipitation and agglutination assays.
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.