Medical Definition of Co-stimulationCo-stimulation: An event in the immune system involving the delivery of a second signal by an antigen-presenting cell. The second signal rescues the activated T cell from anergy (which is a state of immune unresponsiveness), allowing the T cell to produce the lymphokines necessary for the growth of additional T cells. T cells are small white blood cells that orchestrate and directly participate in the immune defenses. Also known as T lymphocytes, they are processed in the thymus (which is why they are called T cells). Last Editorial Review: 6/9/2016 Back to MedTerms online medical dictionary A-Z List Need help identifying pills and medications? |


