CD28

CD28 is a protein found on the surface of T cells, a type of white blood cell crucial for the immune system. It is also known as T-cell costimulatory molecule CD28. CD28 plays a vital role in T cell activation. For a T cell to become fully activated and mount an immune response, it typically requires two signals. The first signal comes from the T cell receptor binding to an antigen presented by an antigen-presenting cell. The second signal, often referred to as the costimulatory signal, is provided by CD28. CD28 binds to its ligands, CD80 and CD86, which are also found on antigen-presenting cells. This interaction is essential for the robust proliferation and cytokine production of T cells, ensuring a strong and effective immune response. Without this costimulatory signal through CD28, T cells may become anergic, a state of unresponsiveness. Therefore, CD28 is considered a critical checkpoint in T cell activation, balancing the need for immune responses with the prevention of autoimmunity. Its importance extends to various immune processes, including the development of adaptive immunity and the regulation of T cell differentiation.