CD80/CD86

CD80 and CD86 are proteins found on the surface of certain immune cells called antigen-presenting cells. They act as "costimulatory signals" that help activate T cells, which are crucial for immune responses. When an antigen-presenting cell recognizes a threat, CD80 and CD86 bind to specific receptors (CD28) on T cells, providing the necessary second signal to fully activate the T cell. This interaction ensures that the immune system responds appropriately to threats like infections or cancer, while preventing overreaction that could harm healthy tissue.