Questions About Cancer? 1-800-4-CANCER

Understanding Cancer Series

  • Posted: 01/28/2005
  • Reviewed: 09/01/2006

Slide 23

:

Activation of T Cells: Cytotoxic

Killer T cells only recognize antigen in the grasp of Class I MHC markers. Here a resting cytotoxic T cell recognizes virus fragments, which are displayed by a macrophage in combination with a Class I MHC marker. A receptor on a circulating, resting cytotoxic T cell (and CD8 protein) recognizes the antigen-protein complex and binds to it. The binding process and an activated helper T cell activate the cytotoxic T cell. Because the surfaces of other infected cells bear the same virus fragments in combination with Class I MHC markers, the activated cytotoxic T cells can quickly recognize, attack, and destroy the diseased cell.

Activation of T Cells: Cytotoxic