Anti-Human CD4 (Clone SK3) – Purified (PhenoCycler-Fusion (CODEX)® Ready)

Clone SK3 has been validated for use on PhenoCycler® using [Mouse/Human] [Tissue] [Tissue Type either FFPE or FF] tissue.

Recombinant protein of human CD4

This purified antibody is formulated in 0.01 M phosphate buffered saline (150 mM NaCl) PBS pH 7.4.

This antibody is stable for at least one week when stored at 2-8°C. For long term storage, aliquot in working volumes without diluting and store at -20°C in a manual defrost freezer. Avoid Repeated Freeze Thaw Cycles.

SK3 activity is directed against human CD4.

CD4 is expressed on most thymocytes, a subset of T cells (T helper cells, subsets of memory and regulatory T lymphocytes), monocytes, macrophages, human peripheral blood mononuclear cells, natural killer cells, and may be detected in thymus, lymph nodes, tonsils, and spleen, and also in specific regions of the brain, gut, and other non-lymphoid tissues.

CD4 is a type I transmembrane glycoprotein with four domains and is a member of the Ig superfamily^1,2. CD4 functions primarily as a coreceptor for the MHC class II molecule-peptide complex³. CD4 initiates the early phase of T-cell activation via its association with the T-cell receptor complex and protein tyrosine kinase Lck. In addition, CD4 functions as a mediator of direct neuronal damage in infectious and immune-mediated diseases of the central nervous system. Furthermore, HIV displays tropism for CD4⁺ T cells⁴ and CD4 acts as the primary receptor for HIV viral entry via binding of its extracellular domain with the HIV-1 gp120 surface glycoprotein^2,3.

SK3 can be used as a reference standard in quantitative flow cytometry^5,6 and to study HIV viral entry⁴. SK3 does not compete for binding with Tregalizumab⁷. Since the binding site of Tregalizumab is in close proximity to a disulfide bond in domain 2 of CD4, SK3 binds elsewhere in the CD4 protein. Lisco et al give domain 3 as the binding site⁸.

MHC class II molecules, HIV gp120, IL-16

1. Lynch GW, Turville S, Carter B, et al. Immunol Cell Biol. 84(2):154-165. 2006.
2. Wittlich M, Thiagarajan P, Koenig BW, et al. Biochim Biophys Acta. 1798(2):122-127. 2010.
3. https://www.uniprot.org/uniprotkb/P01730/entry
4. Bouvin-Pley M, Leoz M, Roch E, et al. AIDS. 34(15):2187-2200. 2020.
5. Degheidy H, Abbasi F, Mostowski H, et al. Cytometry B Clin Cytom. 90(2):159-167. 2016.
6. Wang L, Gaigalas AK, DeRose PC. J Res Natl Inst Stand Technol. 123:1-23. 2018.
7. Heim K, Dälken B, Faust S, et al. Clin Transl Immunology. 5(12):e121. 2016.
8. Lisco A, Ye P, Wong CS, et al. J Infect Dis. 223(4):645-654. 2021.
9. Chujo D, Foucat E, Nguyen TS, et al. PLoS One. 8(2):e55595. 2013.
10. Brito LA, Chan M, Shaw CA, et al. Mol Ther. 22(12):2118-2129. 2014.
11. Marin M, Du Y, Giroud C, et al. Assay Drug Dev Technol. 13(3):155-166. 2015.
12. Zischke J, Mamareli P, Pokoyski C, et al. PLoS Pathog. 13(6):e1006454. 2017.