Autoimmunity is an immune reaction against “self.” Autoimmune disease implies that tissue damage is a result of an autoimmune (autoallergic) reaction. This may be the result of antibody production or as a result of lymphocytes (CD4+) causing damage directly or in concert with macrophages.
There is a third type of immunologic reaction, an antibody-mediated tissue damage in which different lymphocytes (CD8+) cause additional damage.
All three types of reactions are thought to play a role in some patients with MS. Recent evidence implicates CD8+ cells in attacks of demyelinating disease called acute disseminated encephalomyelitis that, although resembling MS, does not relapse. It is like a “single attack of MS” type of disease.