KLRK1 and autoimmune disease: However, apart from cancer, the NKG2D system plays a role in several other pathological situations that involve some degree of cellular stress, including transplantation (Collins, 2004; Suarez-Alvarez et al., 2006), autoimmune diseases (Van Belle and von Herrath, 2009), and pathogen infection (Borchers et al., 2006).