In autoimmune meningoencephalomyelitis, the autoantibody targets a protein called glial fibrillary acidic protein within cells called astrocytes that are found in the brain and spinal cord.
“Headache is a prominent symptom reported by the patients,” says Dr. Lennon, who is senior author on the study. “It is accompanied by neurological findings of varying severity. Inflammatory cells in the spinal fluid and MRI images raise suspicion for brain infection, other inflammatory brain disease or a cancer spreading to the lining of the brain.”
Dr. Lennon notes that this disease rapidly reverses with therapy directed at the immune system, such as prednisone, in contrast to infections that need antibiotics and cancer that requires aggressive treatment. A positive test for glial fibrillary acidic protein autoantibody should bring the correct diagnosis earlier and hasten the most appropriate treatment.
The glial fibrillary acidic protein antibody biomarker initially was identified in Mayo Clinic’s Neuroimmunology Laboratory, which is within the Department of Laboratory Medicine and Pathology. The biomarker was identified using a test developed in the 1960s. The process involves applying a patient’s serum or spinal fluid to thin sections of mouse tissues. If an autoantibody is present, it will stick to the targeted tissue. After the serum or spinal fluid is washed off, a probe in the form of another antibody is applied to the tissue to detect any human antibody that remains bound to the tissue. The probe antibody is tagged with a fluorescent dye. When viewed under a fluorescence microscope, the tagged antibody shows the location of the bound human autoantibody, revealing the cells targeted by the immune system. In this case, the pattern of binding to mouse brain tissue resembles the pattern of abnormalities seen in MRI images of the patients’ brain and spinal cord.