cFluor^® V670 anti-Human CD4 (RPA-T4)

The RPA-T4 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 major histocompatibility complex (MHC) class II molecules on antigen-presenting cells. The extracellular domain of CD4 binds to the beta2 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 RPA-T4 antibody is widely used as a phenotypic marker for human CD4 expression and is cross-reactive with chimpanzee CD4. This antibody recognizes a different epitope than the anti-human CD4 antibody clone OKT4, thus does not block binding of CD4 clone OKT4 (Reinherz EL, et al. 1979. Proc. Natl. Acad.