Midkine-like immunoreactivity in extracellular neurofibrillary tangles in brains of patients with parkinsonism-dementia complex of Guam

Midkine (MK) has been shown to be present in amyloid deposits in Alzheimer's disease (AD). In the present study, expression of midkine was examined immunohistochemically in brains of patients with the parkinsonism-dementia complex of Guam, lytico bodig disease (LB), using an affinity purified antibody to midkine. Positive staining was identified on some extracellular neurofibrillary tangles. The relative prevalence was somewhat less than for beta-amyloid protein (alpha beta)-positive extracellular tangles. The results demonstrate that expression of MK and alpha beta is not an exclusive feature of amyloid deposits in Alzheimer brain, but is also found in LB brain.