These drugs are as good as gold.

• Position: Autoimmune Diseases - Work of medicinal metals

Gold components have been used for the treatment of rheumatoid arthritis and other autoimmune diseases for more than 75 years but, until now, how the metals work has been a mystery. Researchers from Harvard Medical School, Boston, report that special forms of gold, platinum, and other classes of medicinal metals work by stripping bacteria and virus particles from the grasp of a key immune system protein.

"We were searching for a new drug to treat autoimmune diseases, but instead we discovered a biochemical mechanism that may help explain how an old drug works," admits Brian DeDecker, a post-doctoral student in the Department of Cell Biology.

DeDecker undertook a large-scale search for new drugs that would suppress the function of an important component of the immune system, MHC class II proteins, which are associated with autoimmune diseases. These proteins normally hold pieces of invading bacteria and virus on the surface of specialized antigen presentation cells.

Presentation of these pieces alerts other specialized recognition cells of the immune system called lymphocytes, which starts the normal immune response. Usually, this response is limited to harmful bacteria and viruses, but sometimes this process goes awry and the immune system turns towards the body itself, causing autoimmune diseases such as juvenile diabetes, Lupus, and rheumatoid arthritis.

During the search through thousands of compounds, DeDecker found that the known cancer drug...