The immunology of multiple sclerosis and its animal model, experimental allergic encephalomyelitis.

Two questions were posed at the beginning of this article. Is EAE a good model for MS? And, is MS an autoimmune disease? The first question is easier to address than the second. EAE is the best available model for the inflammatory processes that occur in MS, and for the disease process. The latter depends somewhat on study of chronic relapsing EAE, rather than early or mono-episodic EAE, which, although of great immunological interest, is of less relevance to the established disease that presents as MS. The second question asks whether MS fulfills Koch's postulates as an autoimmune disease. MS has all the hallmarks of an inflammatory disease of the CNS. The question then is whether the inflammation is autoimmune. The evidence presented shows a considerable autoimmune component to MS inflammation, raising the subsidiary question of whether autoimmune reactivity induces MS. This remains unanswerable for the present, and it should be kept in mind that the same question also would be unanswerable by observation of EAE. The major postulate therefore remains unfulfilled. Diagnosis of MS as an autoimmune disease requires definitive identification of the autoantigen; otherwise, the possibility remains open that this is a disease resulting from the inadvertent activation and dysregulation of immune processes in the CNS that, themselves, are not directed at that organ.