When injected directly into the brain of mice, antibodies against a plaque protein retarded growth of the plaques by up to two months. No adverse side effects were found.
"By injecting the antibodies directly into the brain, we were able to circumvent the problems others have encountered in developing a vaccine for this terrible disease," said Neelima Chauhan, research assistant professor in the UIC College of Medicine.
Results of the study appear in the current issue of the Journal for Neuroscience Research.
Two methods of immunization have been tried in Alzheimer's disease. In the first, called active immunization, researchers inject the antigen itself -- pieces of the sticky beta amyloid protein that constitutes the plaques -- into patients to spur the production of antibodies that should neutralize the protein and prevent it from accumulating in brain cells.
But after success in animals, clinical trials of active immunization failed when 6 to 8 percent of the patients in the study developed meningocephalitis, an inflammation of the tissue surrounding the brain.
Passive immunization did not even succeed in animal studies. In this method, researchers inject ready-made antibodies, rather than the antigen, into the animal. But high concentrations of the antibodies are required to be effective, and the large doses were found to cause hemorrhaging and inflammation.
Aware of such problems, Chauhan tried a modified passive immunization method in laboratory mice that are used as a model for the disease. In a single injection, she delivered the antibody directly into the third ventricle, a narrow cavity located between the two hemispheres of the brain, and then examined the animals' brain tissue at one, four and
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Contact: Sharon Butler
sbutler@uic.edu
312-355-2522
University of Illinois at Chicago
26-Oct-2004