The CD4 antigen is involved in the recognition of the type II MHC antigen. It is also a receptor for HIV. It is present on most T helper cells and normal thymocytes. The cytoplasmic portion of CD4 is associated with p56lck tyrosine kinase. CD4 expression is commonly found in human lymph nodes and tonsils. CD27 (50 kDa) is a member of the tumor necrosis factor (TNF) receptor superfamily. CD40 and CD30 are also members of the TNF receptor superfamily. The TNF superfamily members are known for the regulation of cell proliferation and death. In contrast to the expression of other TNFR/TNF family members, expression of CD27 and its ligand CD70 is predominantly confined to lymphocytes. High expression levels of CD27 appear to be dependent on proper ligation of antigen receptors. CD70 expression requires additional co-stimulatory and/or pro-inflammatory signals. CD27 is a membranebound receptor, but a soluble form of CD27 is also produced.
CD27; CD27 antigen; CD27L receptor; CD4; CD4 antigen (p55); CD4 antigen p55; CD4 receptor; sCD27; soluble CD27; T cell activation antigen S152; T-cell activation antigen CD27; T-cell surface antigen T4/Leu-3; T-cell surface glycoprotein CD4; T14; Tumor necrosis factor receptor superfamily member 7; tumor necrosis factor receptor superfamily, member 7