The GR20 monoclonal antibody specifically binds to CD119, the α chain of the interferon γ (IFN-γ) receptor. This receptor is expressed by mouse leukocytes, endothelial, and epithelial cells, but not by mature erythrocytes. GR20 mAb recognizes an epitope (susceptible to certain fixatives) in the ligand-binding site of the receptor. It can block the binding of mouse IFN-γ; therefore, it can inhibit IFN-γ .mediated effects including the activation of mouse macrophages for tumor cell killing. IFN-γ has been reported to induce the expression of Ly-6A/E antigen on cell lines and normal B lymphocytes, and the GR20 antibody is capable of inhibiting the IFN-γ.induced expression of Ly-6A/E on the mouse B lymphoma line A20. The binding of the GR20 antibody to CD119 is inhibited by IFN-γ. This antibody reportedly does not have any agonist effect.
This antibody is conjugated to BD Horizon™ BV605 which is part of the BD Horizon Brilliant™ Violet family of dyes. With an Ex Max of 407-nm and Em Max of 602-nm, BD Horizon BV605 can be excited by a violet laser and detected with a standard 610/20-nm filter set. BD Horizon BV605 is a tandem fluorochrome of BD Horizon BV421 and an acceptor dye with an Em max at 605-nm. Due to the excitation of the acceptor dye by the green (532 nm) and yellow-green (561 nm) lasers, there will be significant spillover into the PE and BD Horizon PE-CF594 detectors off the green or yellow-green lasers. BD Horizon BV605 conjugates are very bright, often exhibiting brightness equivalent to PE conjugates and can be used as a third color off of the violet laser.