The S5.2 monoclonal antibody specifically recognizes the CD2 antigen, a 45 to 50 kDa type I transmembrane glycoprotein that forms the binding site for sheep erythrocytes. The CD2 antigen is present on approximately 75% of normal peripheral blood lymphocytes and 95% to 99% of thymocytes. It is also found on a subset of monocytes (approximately one-third) that might be precursors to dendritic cells. The CD2 antibody reacts with essentially all T lymphocytes and with a subset of NK lymphocytes. CD2 and CD58 have been shown to be coreceptors. The interaction of CD2 antigen and CD58 antigen facilitates antigen recognition by T lymphocytes.
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.