The OX-34 antibody reacts with CD2 (LFA-2), a member of the immunoglobulin superfamily. In the rat, CD2 is expressed on thymocytes, T lymphocytes in spleen and lymph node, dendritic epidermal T cells, splenic macrophages, and NK cells, but not on B cells, most intestinal intraepithelial lymphocytes, or peritoneal and liver macrophages. CD2 can associate with the T-cell receptor complex, and it may function in both intercellular adhesion and signal transduction. In the rat, CD48 and CD59 have been identified as ligands for CD2. OX-34 mAb binds to the extracellular portion of CD2, and it blocks the binding of CD2 to CD48. While OX-34 antibody does not activate T cells, it partially blocks activation by immobilized mAbs to CD3 (clone G4.18) and αβ T-cell receptor (clone R73), and it partially inhibits allogeneic mixed lymphocyte reactions. Moreover, in vivo administration of OX-34 antibody depletes peripheral T cells and prevents allograft rejection.
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.