The OX-19 antibody reacts with CD5, a 69 kDa cell-surface glycoprotein found on thymocytes, peripheral T lymphocytes, and some thymic dendritic cells, but not on alloantigen-activated cytotoxic T cells, NK cells, γδ TCR-bearing intestinal intraepithelial lymphocytes, or dendritic epidermal T cells. A CD5+ subset of B lymphocytes has not been characterized in the rat. In the mouse and human, CD72 is the major ligand for CD5. While the OX-19 antibody is not mitogenic, its presence augments in vitro proliferative responses of T cells to lectins and allogeneic cells.
The antibody was conjugated to BD Horizon™ BUV496 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 496-nm. BD Horizon BUV496 can be excited by the ultraviolet laser (355 nm) and detected with a 515/30 nm filter with a 450LP. Due to the excitation of the acceptor dye by other laser lines, there may be significant spillover into the channel detecting BD Horizon V500 or BV510 (eg, 525/40-nm filter). However, the spillover can be corrected through compensation as with any other dye combination.