Enzyme-linked immunosorbent assay for human autoantibody to glial fibrillary acidic protein: higher titer of the antibody is detected in serum of patients with Alzheimer's disease.

We have developed an enzyme-linked immunosorbent assay (ELISA) to detect anti-glial fibrillary acidic protein (GFAP) autoantibody in human sera. The ELISA was prepared by coating microtest plates with purified GFAP from bovine spinal cord. The autoantibody activities were assayed in the serum from 219 control subjects, 39 Alzheimer's disease patients and 39 cerebrovascular dementia patients. Higher titer of the antibody was observed in the serum of Alzheimer's disease patients. Since the titer showed no significant change with aging or with sex in the control serum, we could determine a certain normal value of the antibody titer. The percentage of abnormal subjects whose antibody levels were over the normal value was 53.8% in Alzheimer's disease (presenile onset) patients, 30.8% in Alzheimer's disease (senile onset) patients, 10.3% in cerebrovascular dementia patients and 5.5% in control subjects. We discuss the relationship between the anti-GFAP autoantibody and the pathogenesis of Alzheimer's disease and suggest that the evaluation of anti-GFAP autoantibody level may be useful in diagnosing Alzheimer's disease.