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™ BUV563 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 which has an Ex Max of 348 nm and an acceptor dye. The tandem has an Em Max at 563 nm. BD Horizon BUV563 can be excited by the 355 nm ultraviolet laser. On instruments with a 561 nm Yellow-Green laser, the recommended bandpass filter is 585/15 nm with a 535 nm long pass to minimize laser light leakage. When BD Horizon BUV563 is used with an instrument that does not have a 561 nm laser, a 560/40 nm filter with a 535 nm long pass may be more optimal. Due to the excitation and emission characteristics of the acceptor dye, there may be spillover into the PE and PE-CF594 detectors. However, the spillover can be corrected through compensation as with any other dye combination.