Breakthrough hope in flu fight

28 July 2008 12:07am

Flu symptoms can be "switched off" by targeting a biological immune system regulator in the lungs, a study has shown.

Scientists hope the discovery will pave the way to effective new treatments for flu and other lung infections.

When flu strikes, most of the problems it causes - such as breathlessness, weight loss and fever - are due to over-reaction by the immune system rather than the influenza virus.

Long after the virus is cleared from the body, the immune response continues, leading to inflammation and clogged airways.

The same kind of over-reaction occurs in a number of other diseases, including asthma and inflammatory gut conditions such as Crohn's.

The new research focused on a biological mechanism in the lungs which normally keeps the immune system under control.

Researchers at Imperial College London found a "receptor" protein called CD200R that acts like a switch to limit the immune response and halt inflammation once it has started.

But for the switch to be "flipped" another protein, CD200, has to bind to it, slotting onto the molecule like a key in a lock.

Flu overrides CD200 so that the immune system regulator is not engaged, and inflammation results.

Experiments with mice showed that it was possible to use an artificial molecule or antibody with similar properties to CD200 to throw the "switch" by binding onto the receptor. Mice treated in this way suffered less weight loss and inflammation in the lungs and airways than other flu-infected animals.

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