Blood test to detect Alzheimer’s developed

Updated: Jan 07, 2011, 00:00 AM IST

Washington: A novel technology that is able to detect the presence of immune molecules specific to Alzheimer’s disease in patients`` blood samples has been developed by the scientists from the Florida campus of The Scripps Research Institute.

While still preliminary, the findings offer clear proof that this breakthrough technology could be used in the development of biomarkers for a range of human diseases.

The new study, challenges conventional wisdom and uses synthetic molecules rather than antigens to successfully detect signs of disease in patients`` blood samples.

These synthetic compounds have many advantages – they can be modified easily and can be produced quickly in relatively large amounts at lower cost.

To test the concept, Scripps Research Professor Thomas Kodadek and his colleagues used comparative screening of combinatorial libraries of synthetic molecules – peptoids – against serum samples obtained from mice with a multiple-sclerosis-like condition or healthy controls. Those synthetic molecules that retained more immunoglobulin (IgG), a major type of antibody, from the blood samples of the diseased animals were identified as potential agents for capturing diagnostically useful molecules. This worked well.

The team next turned to serum samples from six Alzheimer’s patients, six healthy individuals, and six Parkinson’s disease patients. Three peptoids were identified that captured at least three-fold higher levels of IgG antibodies from all six of the Alzheimer’s patients than any of the control or Parkinson’s patients. The results showed that two of the peptoids bind the same IgG antibodies; a third binds different antibodies, resulting in at least two candidate biomarkers for the disease.

"We use these peptoids as a lure to capture the IgG antibodies," Kodadek said.

"Some of these synthetic molecules recognize the antigen-binding sites of disease-specific antibodies well enough to pull them from blood samples, although they almost certainly don’t bind as well as the native antigens. This ability should make it possible to short circuit the discovery of the natural antigens."

The study has been published in the edition of the journal Cell.