The CMRF-56 monoclonal antibody specifically binds to a 96 kDa, early activation/differentiation antigen expressed on dendritic cells (DCs). The CMRF-56 antigen is expressed on isolated Langerhans cells, dermal DCs, migratory dermal DCs and monocyte derived DCs (GM-CSF, IL-4, TNF-α). Circulating blood DCs are CMRF-56-, but its expression is induced within 6 hrs of in vitro culture. Tonsil and synovial fluid DCs upregulate CMRF-56 expression following short-term in vitro culture. It is not detected on resting peripheral blood leukocytes, but is on a subpopulation of tonsil B cells and on in vitro cultured CD19+ cells. CMRF-56 was generated using the Hodgkin's-derived L428 cell line as immunogen. This reagent could be useful in flow cytometric or immunomagnetic separation procedures and immunohistochemical staining of acetone-fixed frozen tissue sections.
The antibody was conjugated to BD Horizon™ BUV661 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 with an Ex Max of 348-nm and an acceptor dye with an Em Max at 661-nm. BD Horizon Brilliant BUV661 can be excited by the ultraviolet laser (355 nm) and detected with a 670/25 filter and a 630 nm LP. Due to cross laser excitation of this dye, there may be significant spillover into channels detecting APC-like emissions (eg, 670/25-nm filter).
Due to spectral differences between labeled cells and beads, using BD™ CompBeads can result in incorrect spillover values when used with BD Horizon BUV661 reagents. Therefore, the use of BD CompBeads or BD CompBeads Plus to determine spillover values for these reagents is not recommended. Different BUV661 reagents (eg, CD4 vs. CD45) can have slightly different fluorescence spillover therefore, it may also be necessary to use clone-specific compensation controls when using these reagents.