Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to certain organs (e.g. in thyroiditis) or involve a particular tissue in different places (e.g. Goodpasture's disease which may affect the basement membrane in both the lung and the kidney). The treatment of autoimmune diseases is typically with immunosuppression—medication which decreases the immune response.

Common autoimmune diseases are:

-Addison's Disease

-Celiac Disease

-Dermatomyositis

-Grayes Disease

-Hashimoto's Thyroiditis

-Multiple Sclerosis

-Myasthenia Gravis

-Pernicious Anemia

-Reactive Arthritis

-Rheumatoid Arthritis

-Sjogren Syndrome

-Systemic Lupus Erythematosus

-Type I Diabetes

Symptoms are varied because there are so many autoimmune diseases. An autoimmune disorder may result in the destruction of one or more types of body tissue, abnormal growth of an organ, or changes in organ function. Organs and tissues commonly affected by these disorders are:

-Blood Vessels

-Connective Tissues

-Endocrine Glands; such as the thyroid or pancreas

-Joints

-Muscles

-Red Blood Cells

-Skin

Because hemp and cannabinoids can aid in healing skin rashes or dry skin, areas of skin affected by autoimmune diseases such as psoriasis (a disorder that occurs commonly with autoimmune disorders such as AIDS or rheumatoid arthritis) can be treated effectively. In autoimmune disease, connective tissues can experience pain, which cannabis is also reported to temper.

In a study called "Direct Suppression of Autoreactive Lymphocytes in the Central Nervous System Via the CB2 Receptor" by BloodCenter of Wisconsin at the Blood Research Institute, it was found that "The cannabinoid system is now recognized as a regulator of both the nervous and immune systems […] The best-studied plant cannabinoid, Δ9-tetrahydrocannabinol (THC), produced by Cannabis sativa and found in marijuana, has shown evidence of being immunosuppressive in both in vivo and in vitro." Therefore, cannabis has an immunosuppressive quality, very beneficial for those who suffer from autoimmune diseases.

http://www.nlm.nih.gov/medlineplus/ency/article/000816.htm