Anti-Hu CD4, OKT4, BT, 100µg

A mouse monoclonal antibody from STEMCELL Technologies, clone OKT4, targets the human CD4 antigen for research use. CD4 is described as a single-chain type I transmembrane glycoprotein of ~59 kDa 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.

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 that enhances the affinity of the T cell receptor (TCR) for the MHC II–antigen complex during MHC II-restricted antigen recognition; its intracellular domain also interacts with cytoplasmic tyrosine kinases such as Lck. CD4 additionally serves as a receptor for the human immunodeficiency virus (HIV), although binding of OKT4 does not block HIV attachment.

The manufacturer describes the antibody as suitable for flow cytometry applications, with figure data showing staining of human peripheral blood mononuclear cells (PBMCs) under several conjugations. Related formats are offered as biotin, FITC, PE, APC, Alexa Fluor 488, PerCP-Cy5.5, and unconjugated presentations. The clone has been verified for purity assessments of cells isolated with EasySep™ kits for CD4+ T cell isolation, CD3 positive selection, and direct CD4+ T cell isolation, and the biotin-conjugated format has been demonstrated using streptavidin APC secondary detection.