Neuroimmunology I: Immunoregulation in neurological disease.

Aberrations in immune function that ultimately result in disease states may involve three aspects of immune regulation: (1) regulatory T cells, which both suppress and induce immune responses; (2) idiotype-antiidiotype networks, which serve as internal regulatory networks during generation of an immune response; and (3) immune response genes, which determine genetic differences in an individual's immune response. Three major diseases of the nervous system, multiple sclerosis, myasthenia gravis, and acute inflammatory polyneuropathy (Guillain-Barré syndrome), are classified as "autoimmune" in nature and may be due to underlying disorders of immunoregulation. In multiple sclerosis there is a loss of suppressor T cells in the peripheral blood during attacks, in myasthenia gravis there are thymic abnormalities and antibodies against the acetylcholine receptor, and in acute inflammatory polyneuropathy, macrophage-mediated destruction of peripheral nerve myelin occurs in the context of sensitized T cells and is usually associated with a preceding viral illness. In each of these diseases the following central questions must be answered: (1) against what antigen (or antigens) of the nervous system is the autoimmune response directed? (2) what is the mechanism of immune damage? and (3) what initiates, or triggers, the autoimmune response?