Why vCJD is more common in young people Certain cells in the immune system could help to explain why young people are more likely to develop variant Creutzfeldt-Jakob Disease (vCJD) than older people. The findings, published in the Journal of Immunology, could eventually result in new tests for the disease and treat... Certain cells in the immune system could help to explain why young people are more likely to develop variant Creutzfeldt-Jakob Disease (vCJD) than older people. The findings, published in the Journal of Immunology, could eventually result in new tests for the disease and treatments to stop the disease-causing prions from spreading to the brain and central nervous system (CNS). The study was supported in part by the EU-funded NEUROPRION ('Prevention, control and management of prion diseases') project, which is financed through the 'Food quality and safety' Thematic area of the Sixth Framework Programme (FP6). Variant CJD is caused by an abnormal kind of protein called a prion. People become infected by eating meat products derived from cows that were infected with BSE (bovine spongiform encephalopathy). In contrast to other forms of CJD, vCJD patients tend to be rather young; the average age at the onset of symptoms is just 28. The reason for this has puzzled scientists for some time. Theories based on the idea that young people eat more burgers and sausages (which tended to contain more brain and spinal cord material before these were banned in food for human consumption), did not seem to hold much water as most of the population had also eaten these products. In this study, UK researchers looked at immune cells called follicular dendritic cells (FDCs) in mice infected with a version of the prion disease scrapie. FDCs are found in tissues such as the spleen, lymph nodes and tonsils. When the disease prions first enter the body, the FDCs attract the prions and cause them to multiply. In older mice, the FDCs are significantly weaker, and so are less able to attract prions. The researchers found that the spleens of older mice contained relatively low levels of prions, and none of the older mice developed scrapie symptoms. In contrast, the younger mice did fall ill. 'It has always been unclear why younger people were more susceptible to variant CJD, and the assumption that they were more likely to eat cheap meat products is far too simplistic,' commented Dr Neil Mabbott of the Roslin Institute at the University of Edinburgh. 'Understanding what happens to these cells, which are important for the body's immune responses, could help us develop better ways of diagnosing variant CJD or even find ways of preventing prions from spreading to the brain. It could also help to create a vaccine.' The study also raises concerns that more people may be infected than had previously been suspected. Although none of the elderly mice developed symptoms of the disease and their lymphoid tissues appeared to be disease free, on autopsy, many were found to have signs of the disease in their brains. This is important because until now, researchers have used information on the presence of prions in tonsil and appendix tissue samples to estimate how many people may be infected. These latest findings suggest that the prions may die off in lymphoid tissues after they have spread to the brain. In addition, the results imply that there may be 'significant levels of subclinical disease in the elderly population'. According to the latest data, there have been a total of 170 cases of vCJD in the UK since the first cases were recorded in 1995. Additional cases have been recorded in 10 other countries; many of these patients had spent some time in the UK between 1980 and 1996. Currently there is no cure for the disease, and patients die an average of 14 months after falling ill. Countries United Kingdom
