Developmental changes of apolipoprotein E immunoreactivity in Down syndrome brains.

The temporal profile of apolipoprotein-E (apo-E) expression was investigated immunohistochemically in the brains of Down syndrome patients and of normal controls. The number of apo-E immunoreactive astrocytes in the frontal cortex was larger in Down syndrome patients than in controls from 7 months to 24 years of age. It suggests that apo-E producing astrocytes in the early phase of pathological process lead to presenile dementia in Down syndrome patients. In contrast, the number in the white matter was smaller in Down syndrome patients from 28 gestational weeks to 5 years. Apo-E immunoreactive senile plaques were noted in Down syndrome brains from the age of 25 years, while APP immunoreactivity was first noted in senile plaques at the age of 32 years.