Spontaneous autoimmune disease models exist as a result of deliberate inbreeding of strains of animal for particular characteristics including the incidence of autoimmune disease. Such inbred strains are therefore genetically susceptible and individuals spontaneously develop disease. Examples of this type of model are the obese strain chicken (thyroiditis) and the NOD mouse (diabetes). Generally the cumulative incidence is less than 100%, in some cases much less.

Induced autoimmune disease models require some treatment of the animal to trigger the disease. They also generally require the presence of some genetic susceptibility factors. For example the injection mice with spinal chord extract and powerful adjuvants will trigger an autoimmune encephalomyelitis (EAE) but only in a few inbred strains. This disease resembles multiple sclerosis.

Disease mechanisms

Mechanistic studies are virtually impossible in humans so most of our understanding comes from the development and analysis of animal models.

The NOD mouse model of diabetes (IDDM) has shown that the disease process involves CD8⁺ and CD4⁺ T cells and macrophages. It has also demonstrated the requirement for a specific MHC class II susceptibility allele and is proving useful in examining the role of the other dispersed susceptibility loci ( of which there are 15 mapped). It has also shown that inducing tolerance to candidate antigens of which insulin is only one, will prevent the development of disease.

Induced models such as EAE have an advantage in that the triggering stimulus can be studied and the autoantigen is usually known. EAE can be transferred with a single clone of T cells.

Information provided by: http://www-immuno.path.cam.ac.uk