CD4 is a member of the cluster of differentiation family of proteins, mainly expressed on the surface of thymocytes and a specific subset of mature T-cells. CD4 antibody studies have also shown it expressed on monocytes, cortical cells, microglial cells, dendritic cells and macrophages. The CD4 antibody is widely used in cell marker studies, CD4 being one of the most common CD markers in use. However, the CD4 products in our antibody catalog have also proven useful in cell biology, immunology and cytokine research.
CD4 is a co-receptor for the TCR (T Cell Receptor) heterodimer. It has both intracellular and extracellular domains. The intracellular domain amplifies TCR signalling by activating the tyrosine kinase LCK enzyme, essential to the activated T cell signaling cascade. The four extracellular domains interact directly with MHC class II molecules, which are released by antigen-presenting cells. The main function of CD4 is to increase interaction between the TCR and antigen-class II MHC complex.
CD4 antibody studies have shown CD4, together with CD3 chains and the CD8 co-receptor, aids signal transduction through the TCR. The CD4 antibody is useful in distinguishing T-helper from T-cytotoxic cells, both of which express the TCR, as CD4 is specific to T-helper cells while CD8 is expressed on T-cytotoxic cells.
The CD4 antibody is central to HIV research, as the viral envelope protein achieves entry into the host cell by CD4 binding, lowering CD4 levels. The CD4 antibody is routinely used in the CD count test, used to monitor CD levels in HIV positive patients.
Novus Biologicals offers many CD4 reagents for your research needs including: