CD27
Overview
CD27 is a member of the tumor necrosis factor receptor superfamily (TNFRSF) and is a protein that is found on the surface of certain immune cells. It is a type I transmembrane protein that is primarily expressed on T cells, B cells, and natural killer cells. CD27 is a crucial component in the regulation of T cell activation and immune response, as it plays a pivotal role in cell survival, proliferation, and differentiation.
Structure
The CD27 protein is a 55-kDa type I transmembrane glycoprotein. It is composed of an extracellular domain, a transmembrane domain, and a cytoplasmic domain. The extracellular domain of CD27 contains four cysteine-rich domains (CRDs) that are characteristic of the TNFRSF. The cytoplasmic domain of CD27 contains a death domain, which is a protein interaction module that is involved in the regulation of apoptosis and immune responses.
Function
CD27 is a costimulatory molecule that is involved in the regulation of T cell responses. It is expressed on naive T cells and is upregulated upon T cell activation. The interaction of CD27 with its ligand, CD70, provides a costimulatory signal that is required for T cell activation and proliferation. CD27 also plays a role in the regulation of B cell responses, as it is involved in the induction of immunoglobulin class switching and the generation of memory B cells.
Role in Immune Response
CD27 plays a critical role in the immune response. It is involved in the activation and differentiation of T cells, the generation of memory T cells, and the induction of immunoglobulin class switching in B cells. CD27 also plays a role in the regulation of the immune response, as it can modulate the activity of regulatory T cells and inhibit the activity of effector T cells. Furthermore, CD27 is involved in the regulation of the immune response to viral infections, as it is required for the generation of effective antiviral T cell responses.
Clinical Significance
Alterations in the expression or function of CD27 can lead to immune dysregulation and disease. Mutations in the CD27 gene have been associated with a rare form of primary immunodeficiency known as CD27 deficiency. This condition is characterized by recurrent viral infections, hypogammaglobulinemia, and a lack of memory B cells. CD27 is also a potential target for immunotherapy, as it is expressed on various types of cancer cells and can be targeted with monoclonal antibodies to enhance the immune response against cancer.