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The role of tolerance in uveitis

Self-tolerance, the ability to distinguish self from foreign antigens, is critical to the prevention of ocular autoimmunity.[76]Central tolerance involves the elimination of self-reactive T-cell clones during thymic maturation of lymphocytes, whereas peripheral tolerance involves regulatory elements that prevent the expression of autoimmunity once immunoreactivity against self-antigen has been established. During thymic T-cell maturation, the positive selection of T cells capable of reacting against foreign antigen presented by antigen-presenting cells first occurs; in negative selection, T cells reactive against self-antigen are clonally deleted to mediate central tolerance. Animal studies by Egwuagu et al demonstrated that thymic expression of retinal antigens was correlated to resistance to EAU. In their study, murine, rat, and primate strains in which thymic expression of the retinal antigen IRBP was not observed were susceptible to the development of …