The L306.4 monoclonal antibody specifically recognizes CD58 which is also known as Lymphocyte function-associated antigen-3 (LFA-3) or Ag3. CD58 is a ~40 to 65 kDa cell-surface glycoprotein that belongs to the immunoglobulin superfamily. The CD58 antigen mediates cellular adhesion and participates in signal transduction when it binds to its ligand, the CD2 antigen. Cellular interactions regulated by the CD58/CD2 antigens are involved in the antigen-independent adhesion pathway and cytotoxic T lymphocyte (CTL) activity. The CD58 antigen has two isoforms. One isoform is anchored in the cell membrane by a glycophosphatidyl inositol tail, while the other is a type I transmembrane glycoprotein which has a transmembrane hydrophobic segment and a cytoplasmic segment composed of 12 amino acids. The CD58 antigen is widely distributed on cells of both hematopoietic and nonhematopoietic origin. The CD58 antigen is expressed on approximately 40% to 60% of peripheral blood lymphocytes, including CTL. It is also expressed on monocytes, granulocytes, B lymphoblastoid cell lines (such as JY and Daudi), platelets, vascular endothelium and smooth muscle, fibroblasts, and approximately 40% of bone marrow cells.
The antibody was conjugated to BD Horizon™ BUV661 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 661-nm. BD Horizon Brilliant BUV661 can be excited by the ultraviolet laser (355 nm) and detected with a 670/25 filter and a 630 nm LP. Due to cross laser excitation of this dye, there may be significant spillover into channels detecting APC-like emissions (eg, 670/25-nm filter).
Due to spectral differences between labeled cells and beads, using BD™ CompBeads can result in incorrect spillover values when used with BD Horizon BUV661 reagents. Therefore, the use of BD CompBeads or BD CompBeads Plus to determine spillover values for these reagents is not recommended. Different BUV661 reagents (eg, CD4 vs. CD45) can have slightly different fluorescence spillover therefore, it may also be necessary to use clone-specific compensation controls when using these reagents.