The A59 monoclonal antibody specifically recognizes CD89. CD89 is the Fc receptor for IgA (FcαR), a 55-75 kDa glycoprotein expressed exclusively on cells of granulocytic and monocyte/macrophage lineages in peripheral blood, but not on lymphocytes. It is also expressed on promyelocytes in bone marrow and in the cytoplasm of fixed monocytes. This mAb does not block IgA binding and is more efficient than native IgA ligands in the isolation of FcαR molecules. FcαR plays a role in triggering phagocytosis and respiratory burst.
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.