The OKT4 antibody reacts with human CD4, a 59 kDa protein which acts as a co-receptor for the T cell receptor (TCR) in its interaction with MHC Class II molecules on antigen-presenting cells. The extracellular domain of CD4 binds to the beta-2 domain of MHC Class II, while its cytoplasmic tail provides a binding site for the tyrosine kinase lck, facilitating the signaling cascade that initiates T cell activation. CD4, and co-receptors CCR5 and CXCR4, may also be utilized by HIV-1 to enter T cells. Human CD4 is typically expressed on thymocytes, some mature T cell populations such as Th17 and T regulatory (Treg) cells, as well as on dendritic cells. The OKT4 antibody is widely used as a phenotypic marker for CD4 expression. It is cross-reactive with CD4 in several non-human species, including Chimpanzee, Cynomolgus and Rhesus. This antibody recognizes a different epitope, and thus does not block binding of, the alternative Anti-Human CD4 antibody clone RPA-T4 (Reinherz EL, et al. 1979. Proc. Natl. Acad. Sci. 76:4061-4065).

This mouse monoclonal antibody Anti-CD4 (human), APC & clone OKT4 validated for use in western blotting, IP, ICC, Immunofluorescence and Flow Cytometry for the detection of CD4.

This antibody recognizes a different epitope, and thus does not block binding of Anti-human CD4, clone RPA-T4.

Purified mouse monoclonal antibody in buffer containing 10 mM NaH2PO4, 150 mM NaCl, <0.2% BSA, pH 7.2, and up to 0.1% sodium azide.

The monoclonal antibody was purified from tissue culture supernatant via affinity chromatography. The purified antibody was conjugated under optimal conditions, with unreacted dye removed from the preparation.

Flow Cytometry Analysis: 0.125 µg of this antibody detected CD4 in one million human peripheral blood lymphocytes.