Autoimmune disease: Conceptual history and contributions of ocular immunology.

Medical historians identify the mid-20th century as the time when the scientific and medical communities acknowledged the existence of autoimmune disease. Several conditions including sympathetic ophthalmia and endophthalmitis phacoanaphylactica, however, were proposed as autoimmune disorders much earlier. During the first half of the century, autoimmune disease was viewed as biologically implausible. Paul Ehrlich coined the term horror autotoxicus to emphasize that autoimmunity would contradict nature's aversion to self-injury. The discoveries of allergy and anaphylaxis were the first clues that the immune system was capable of self-harm. A major obstacle to comprehending the pathogenesis of autoimmunity was how the immune system distinguishes foreign from self, a process eventually understood in the context of immune tolerance. Investigators of sympathetic ophthalmia and endophthalmitis phacoanaphylactica were positioned to invalidate horror autotoxicus but lacked sufficiently convincing experimental and clinical evidence to accomplish the task. Seminal studies of chronic thyroiditis and a series of clinical laboratory breakthroughs led to the general acceptance of autoimmune disease in the 1950s. The travails encountered by ophthalmic investigators offer insights into the how medical ideas take shape. We review the contributions of ocular immunology to the conceptual development of autoimmune disease and explore the reasons why the concept caught on slowly.