Protein Can Provoke Immune Attack On Cells

Multiple sclerosis is a debilitating condition that is caused by the body’s immune system attacking the myelin sheath which acts as a protective insulator for the extensive neurons which acts as a pathway for electrical signals from the brain to the other parts of the body. At least, this is what most of the medical experts assume as the primary cause of multiple sclerosis. But some MS patients have also been known to exhibit certain damage on the brain’s gray matter. How extensive the damage is to the gray matter can determine how certain disabilities develop.

Researchers may have found a possible connection for the immune system attack on the myelin sheath as well as on the neurons found on the brain’s gray matter. An international research team headed by Professor Edgar Meinl of LMU Munich has discovered that a certain protein called Contactin-2 is being produced in both the myelin and by the neurons in the gray matter. This can be a possible target of attacks by the misdirected immune system in multiple sclerosis.

It has previously been assumed that in multiple sclerosis, the immune system only attacks the myelin sheath that leads to further damage in the neurons once the myelin insulation breaks down. It is a recent discovery that the immune system in multiple sclerosis may also attack the gray matter along with the myelin sheath in the early stages of the disease. "This extensive damage is a factor in the advancement of the symptoms," says Professor Meinl. "Until now, it has been unclear which molecules direct the immune system against the gray matter".

The researchers conducted large scale tests to find out which proteins found in human brain tissue that the antibodies of MS patients attach into instead of into foreign bodies as they are supposed to. During the course of the tests, the researchers discovered that antibodies dock into the protein Contactin-2, a protein produced in the body but provokes an attack from the immune system in people with MS. In animal model testing, the immune system’s T-cells responded to an animal protein called TAG-1 that is similar to the human Contactin-2.

The TAG-1 protein triggered the T-cells to attack and caused an inflammation in the brain. The attack also opened the blood-brain, the barrier that most cells and molecules normally can’t penetrate. With the barrier opened, this leads the way for more of the gray matter to be attacked by the T-cells more severely. Professor Meinl will try to do further studies if such effects may also take place in human MS patients and on what roles antigens play when they get inside the neurons.

Source: Ludwig-Maximilians-Universitaet Muenchen (LMU). "Gray Matter Under Attack In Multiple Sclerosis: Protein Could Provoke Immune Attack On Several Cell Types." ScienceDaily 7 May 2009. 19 May 2009

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