When The Body Attacks Itself

The immune system is what keeps most people's bodies healthy and free of disease, but for as many as 23 million Americans, it is a cause of disease, too. In autoimmune disorders, the system goes haywire, mistaking the body's own tissues for foreign invaders and destroying them. Drugs for these conditions, which include type 1 diabetes, multiple sclerosis and lupus, have been elusive. But on Sunday, scientists are reporting in the journal Nature that they have found a set of 30 genes that go awry in autoimmune disorders-and t—at could be potential targets for cures. NEWSWEEK's Mary Carmichael spoke with two of the discoverers, Richard Young, a biologist at the Massachusetts Institute of Technology's Whitehead Institute, and Alexander Marson, an M.D./Ph.D. student in Young's lab. Excerpts:

NEWSWEEK: What do these 30 genes normally do in a healthy person's body?

Richard Young: There was a very, very important discovery made about a decade ago, which was that a specialized class of "regulatory T cells" was controlling the immune system's arms of attack. Now, the million-dollar question is why this wonderful system that keeps you healthy might turn against you and begin to attack your own body. And it turns out that in these autoimmune disorders, there are genetic defects in the regulatory T cells, which would otherwise be a check on the rest of the immune system.

These regulatory T cells can't keep the system in line, and it starts attacking things it shouldn't?

Alexander Marson: Yes. In mice, if you remove all the regulatory T cells, what you see is a massive, multiorgan autoimmune disease. In some common human autoimmune disorders, like multiple sclerosis, there's not a total lack of these cells, but there's a subtler dysfunction. The regulatory T cells are present, but they don't work as well at turning off the other immune cells and preventing them from attacking the body.

What exactly is wrong with the genes in these regulatory T cells? What are they doing that they shouldn't be doing?