Anti-Hu CD4, OKT4, FI, 25tests

A FITC-conjugated mouse monoclonal antibody from STEMCELL Technologies, clone OKT4, directed against human CD4. CD4 is an approximately 59 kDa single-chain type 1 transmembrane glycoprotein and a member of the immunoglobulin superfamily, containing four extracellular Ig-like domains (D1–D4); the OKT4 epitope maps to the D3 domain. The antibody is of the IgG2b, kappa isotype, was raised against human peripheral blood T lymphocytes, and reacts with human, rhesus, cynomolgus, and chimpanzee CD4.

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 and acts as a co-receptor for the T cell receptor in MHC II–restricted antigen recognition. CD4 also serves as a receptor for human immunodeficiency virus (HIV); binding of the OKT4 antibody to CD4 does not block HIV binding. The antibody is verified for flow cytometry and is reported in the same application, including purity assessments of cells isolated with EasySep™ kits.

Supplied as a clear liquid in a phosphate-buffered solution at pH 7.2, containing 0.09% sodium azide and 0.2% (w/v) bovine serum albumin. The antibody is purified by affinity chromatography and conjugated with FITC, and the solution is free of unconjugated FITC. For flow cytometry, 5 μL is suggested per 1 × 10^6 cells in 100 μL, or per 100 μL of whole blood, with titration advised for optimal performance. Store undiluted at 2–8°C; do not freeze and protect from prolonged exposure to light.