∞ generated and posted on 2016.03.20 ∞
Basis of immune system's ability to destroy parasites, pathogens, and cancer cells without negatively impacting healthy body tissues, cells, and structures.
Self, in self tolerance, are these normal body tissues, cells, and structures. The process by which self tolerance is achieved is through negative thymic selection and clonal deletion more generally. That is, in adaptive immunity, lymphocytes do not inherently possess self tolerance but instead those lymphocytes that lack self tolerance are, ideally, eliminated from the body.
Self tolerance provides a selective incentive to parasites and pathogens to resemble body molecules antigenically. Such resemblance, however, can give rise to autoimmune disease. Indeed, autoimmune disease in general occur as a consequence of defects in self tolerance.