The ALMA.16 monoclonal antibody specifically recognizes CD42a. CD42a is a 17-22 kDa type I transmembrane glycoprotein that is also known as Platelet glycoprotein IX (GPIX), or Glycoprotein 9 (GP9). CD42a forms a noncovalently linked complex (GPIb/GPIX/GPV) with CD42b, CD42c and CD42d that may serve as a receptor for von Willebrand factor. It is expressed on platelets and megakaryocytes and is absent on the platelets of patients with Bernadr-Soulier Syndrome (BSS). Although the CD42a function is not fully understood, GPIX glycoprotein is important for the assembly and membrane expression of the CD42 complex and for the maintenance of the functional conformation of CD42b (GPIb).
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.