Introduction
CD4 is a cellular immune response co-receptor that raises the avidity of relationship between an antigen-presenting cell and a T-cell through interaction with non-polymorphic parts of the complex between T-cell receptor and major histocompatibility class II molecules. It directly contributes to transduction of signal via cytoplasmic relationship with the lymphocyte kinase. CD4 also plays a role as the high-affinity receptor for attachment of cells as well as entrance of HIV. The CD4 extracellular part consists of domains that resemble immunoglobulin D1 to D4. This component of the CD4 has been qualified as a recombinant soluble protein, and crystal structures have been identified for ...
