Anti-Hu CD4, RPA-T4, PE, 100tests

A mouse monoclonal IgG1 antibody from STEMCELL Technologies, raised in BALB/c mice, targets human and chimpanzee CD4 and is conjugated to PE (Phycoerythrin). The clone, designated RPA-T4, recognizes an epitope within the D1 domain of CD4, an ~59 kDa single-chain type 1 transmembrane glycoprotein belonging to the immunoglobulin (Ig) superfamily. CD4 contains four extracellular Ig-like domains (D1 – D4) and is expressed at relatively high levels by most thymocytes and by a subpopulation of T cells (T helper cells), and at lower levels by peripheral blood monocytes and macrophages. The immunogen was phytohemagglutinin (PHA)-stimulated human peripheral blood mononuclear cells (PBMCs). Alternative designations for CD4 include Leu-3, L3T4, and T4 (Gene ID: 920).

CD4 binds a nonpolymorphic region of MHC class II and acts as a co-receptor to the T cell receptor (TCR) during MHC II-restricted antigen recognition, enhancing the affinity between the TCR and the MHC II–antigen complex. CD4 also serves as a receptor for the human immunodeficiency virus (HIV). Binding by the RPA-T4 antibody has been shown to block HIV attachment and the mixed lymphocyte reaction (MLR), and to inhibit the activation of CD4+ T cells in vitro by interfering with the association of CD4 and HLA-DR; it also partially blocks binding of the SK3 clone. The RPA-T4 epitope is reportedly sensitive to formaldehyde fixation.

The reagent is supplied as a liquid in phosphate-buffered saline (pH 7.2) containing 0.09% sodium azide, 0.1% gelatin, and < 0.2% (w/v) bovine serum albumin. It was purified by affinity chromatography and conjugated with PE under optimal conditions, and the solution is free of unconjugated PE. Flow cytometry (FC) is the verified and reported application. The reagent should be stored at 2 – 8°C undiluted; it should not be frozen and should be protected from prolonged exposure to light.