Anti-Hu CD4, OKT4, AZ, 100tests

STEMCELL Technologies supplies a mouse monoclonal IgG2b, kappa antibody specific for human CD4. Clone OKT4 is conjugated to allophycocyanin (APC) and is verified for flow cytometry applications, with reported use also in flow cytometry. It cross-reacts with rhesus, cynomolgus, and chimpanzee samples, and was raised against human peripheral blood T lymphocytes.

OKT4 recognises an epitope within the D3 Ig-like domain of CD4, an approximately 59 kDa single-chain type I transmembrane glycoprotein of the immunoglobulin superfamily that contains four extracellular Ig-like domains (D1-D4). CD4 is expressed at relatively high levels by most thymocytes and a subpopulation of T cells (T-helper cells), and at lower levels by peripheral blood monocytes and macrophages. It binds a non-polymorphic region of MHC class II, acting as a co-receptor to the T cell receptor (TCR) in MHC II-restricted antigen recognition by enhancing the affinity of the association between the TCR and MHC II-antigen complex, and it amplifies signals from the TCR to the cytoplasm through interaction of its intracellular domain with cytoplasmic tyrosine kinases such as Lck. CD4 also serves as a receptor for human immunodeficiency virus (HIV); however, OKT4 binding does not block HIV attachment. The antibody has been verified for purity assessments of cells isolated with EasySep™ kits for human CD3+ and CD4+ T cells.

For flow cytometry, the suggested use is 5 μL per 1 × 10⁶ cells in 100 μL, or per 100 μL of whole blood; titration is recommended for optimal performance. The product is supplied in phosphate-buffered solution, pH 7.2, containing 0.09% sodium azide and 0.2% (w/v) bovine serum albumin. It was purified by affinity chromatography and conjugated with APC under optimal conditions, and is free of unconjugated APC and unconjugated antibody. The antibody should be stored undiluted at 2 – 8 °C, protected from prolonged exposure to light, and not frozen.