The full form of CD4 is Clusters of Differentiation 4.
CD4 is a glycoprotein found on the surface of immune cells, including:
- T helper cells: These cells play a crucial role in activating other immune cells, such as B cells and cytotoxic T cells.
- Monocytes: These are a type of white blood cell that differentiates into macrophages and dendritic cells.
- Macrophages: These cells engulf and digest cellular debris, pathogens, and other foreign substances.
- Dendritic cells: These cells present antigens to T cells, initiating an immune response.
CD4 acts as a co-receptor for the T cell receptor (TCR). It assists the TCR in binding to the Major Histocompatibility Complex class II (MHC II) molecules on antigen-presenting cells. This interaction is essential for initiating an adaptive immune response. CD4 is also the primary receptor for HIV (Human Immunodeficiency Virus), allowing the virus to infect and destroy T helper cells, which leads to Acquired Immunodeficiency Syndrome (AIDS).
