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.
The antibody was conjugated to BD Horizon™ BV786 which is part of the BD Horizon Brilliant™ Violet family of dyes. This dye is a tandem fluorochrome of BD Horizon BV421 with an Ex Max of 405-nm and an acceptor dye with an Em Max at 786-nm. BD Horizon BV786 can be excited by the violet laser and detected in a filter used to detect Cy™7-like dyes (eg, 780/60-nm filter).