forbidden clone hypothesis [AS, forbeodan + Gk, klon, a cutting, theoria, speculation] , a proposed explanation for autoimmunity that postulates that clones of cells that can react against the body persist after birth and can be activated by a viral infection or by some metabolic change. It holds that most cells of the immune system attack only foreign antigens, but these clones of cells attack the tissues of the body. Compare sequestered antigens hypothesis.
