New research shows why young people are more prone to CJD

Published on Wednesday 14 October 2009 22:19

CELLS in the immune system could hold the key to why younger people are more susceptible to the human form of mad cow disease, Scottish scientists said yesterday.

Patients diagnosed with variant CJD (vCJD) are just 28 years old on average, and it has been unclear why older people are not affected by the disease to the same extent.

Now researchers at the University of Edinburgh have pinpointed cells which, by working less efficiently than they used to due to age, are thought to hamper the spread of the disease.

Scientists behind the study believe the findings could improve the diagnosis of vCJD and even help develop a vaccine against it.

Analysing mice, researchers at the university's Roslin Institute looked at how the immune system interacted with corrupted proteins, known as prions, which are linked to vCJD.

Prions accumulate in lymphoid tissues – part of the body's immune system, which include the spleen, lymph nodes and tonsils – before spreading to the central nervous system, where they kill off brain cells and cause neurological disease.

The researchers found that the prions essentially "hijack" specific cells in the immune system, known as follicular dendritic cells.

The prions accumulate and replicate on the cells, until they reach a sufficient level to spread to the nerves and the brain.

But the study, funded by the Biotechnology and Biological Sciences Research Council, found that those cells were impaired in older mice.

As a result, they were unable to trap and replicate the corrupted proteins and the mice did not develop clinical disease.

Researchers said their study, in the Journal of Immunology, could explain why vCJD did not affect older humans to the same extent and why it occurred almost exclusively in the young.