The JJ319 monoclonal antibody specifically recognizes CD28, which is expressed on virtually all T lymphocytes bearing αβ T-cell receptors (TCR), on most γδ TCR-bearing T cells, and on a subset of NK cells. In the thymus, CD28 expression is developmentally regulated during the maturation of αβ TCR-bearing T cells. CD28 is a costimulatory receptor required for activation of T cells; its ligands include CD80 (B7-1) and CD86 (B7-2). Soluble JJ319 mAb costimulates the proliferative responses and IL-2 production of CD4+ and CD8+ T cells activated by anti-αβ-TCR mAb R73 (Cat. no. 554910). The alternate anti-rat CD28 mAb JJ316 (Cat. No. 554992) is capable of directly stimulating T cells in vitro and in vivo.
The antibody was conjugated to BD Horizon™ BV650 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 650-nm. BD Horizon BV650 can be excited by the violet laser and detected in a filter used to detect APC-like dyes (eg, 660/20-nm filter). Due to the excitation and emission characteristics of the acceptor dye, there will be spillover into the APC and Alexa Fluor® 700 detectors. However, the spillover can be corrected through compensation as with any other dye combination.