The PO3 monoclonal antibody specifically binds to the B7-2 (CD86) costimulatory molecule, which is expressed on a broad spectrum of leukocytes, including B lymphocytes, T lymphocytes, macrophages, dendritic cells, and Langerhans cells, plus astrocytes. CD86 is expressed at low levels by freshly explanted peripheral B and T cells, and its expression is substantially increased by a variety of T and B cell-specific stimuli with a peak expression after 18-42 hours of culture. In contrast to most naive CD4+ T cells, memory CD4+ T cells express B7-2, both at the mRNA and protein levels. CD86, a ligand for CD28 and CTLA-4, is one of the accessory molecules that plays an important role in T cell-B cell costimulatory interactions. It has been shown to be involved in immunoglobulin class switching and triggering of mouse NK cell-mediated cytotoxicity. CD80 (B7-1) is an alternate ligand for CD28 and CTLA-4. PO3 antibody blocks the in vitro stimulation of T-cell proliferation of T-cell proliferation by soluble anti-CD3e antibody (mAb 145-2C11, Cat. No. 553057) in the presence of CD86-expressing accessory cells. In vivo administration of PO3 mAb can inhibit much of the autoantibody production in (NZB x NZW) F1 mice; and in combination with an anti-CD80 mAb, it can prevent the development and progression of mouse systemic lupus erythematosus-like autoimmune disease.
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.