The 2ST8.5H7 monoclonal antibody specifically recognizes an epitope formed by the combination of CD8 alpha and beta chains. The majority of peripheral blood CD8+ T lymphocytes expresses a CD8αβ heterodimer (32, 30 kilodaltons (kDa)), while CD8+CD16+ natural killer (NK) cells and CD8+ TCR γδ+ T lymphocytes express CD8αα homodimers. The 2ST8.5H7 antibody can therefore be used to selectively bind to CD8+ T cells while excluding CD8+ NK cells. CD8 binds to class I major histocompatibility (MHC) molecules, resulting in increased adhesion between the CD8+ T lymphocytes and target cells. Binding of CD8 to class I MHC molecules enhances the activation of resting T lymphocytes. CD8 is coupled to a protein tyrosine kinase, p56lck. The CD8:p56lck complex can play a role in T-lymphocyte activation through mediation of the interactions between CD8 and the CD3/TCR complex. The CD8β antigen is present on the human suppressor/cytotoxic T-lymphocyte subset. The CD8 antigen is expressed on 19% to 48% of normal peripheral blood lymphocytes and 60% to 85% of normal thymocytes. The 2ST8.5H7 antibody crossreacts with lymphocytes of some nonhuman primate species.
The antibody was conjugated to BD Horizon™ BUV395 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye has been exclusively developed by BD Biosciences to have minimal spillover into other detectors, making it an optimal choice for multicolor flow cytometry. With an Ex Max at 348 nm and an Em Max at 395 nm, BD Horizon BUV395 can be excited with a 355 nm laser and detected with a 379/28 filter.