The effector cells of the immune system are able to recognize the infected cells , transformed , and how recently found , cells of various types of stressors . One way is to recognize the identification of the latter, stress-induced cell surface molecules . The best known receptor involved in this type of reaction is the C -type lectin receptor called NKG2D on NK cells present , TGD lymphocytes , CD8 + lymphocytes and macrophages Tab . Described 4 NKG2D ligand family . These are human molecules MIC A and B ( sometimes also referred to as MICA and MICB ) and ULBP and the mouse RAE -1 and H60 . These particles do not exhibit a close relationship , although all can be characterized as non-classical MHC class I All except ULBP whose expression regulation is more complicated and poorly understood, there are large quantities of stress- damaged cells (e.g., thermal or oxidative ) infected and transformed cells. Recognition of the NKG2D receptor leads to a costimulatory signal transmission or the activation of immune cells and cytotoxic reactions . Phenomena related to the functioning of the immune induced activation of the receptor ligands are potential basis for new solutions in the immunotherapy of cancer.