Reactive microgIia in Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is characterized by a loss of neurons accoinpanied by astrogliosis and spongiform changes in the neuropil. It has been recognized that reactive inicroglia occur in CJD but little is known about the regional distribution and extent of the microglial activation. We have. therefore, examined six brains from cases of sporadic CJD by immunohistochemical labelling of grey and white matter microglia froin frontal, parietal. temporal. and occipital lobes, striatum, thalamus, cerebellum and brain stem with RCA-I, LCA. CD68. HIA-DR. and HAM56. Microglial activation occurred in the grey matter where astrogliosis and prion protein (PrP) deposits were prominent. Processes of activated microglia surrounded the outer rim of spongy vacuoles. A diffuse microglial response was seen in the white matter that was immunophenotypically different from grey matter. Double-labelling with microglial marlters and anti-PrP showed that activated inicroglia did not contain PrP-immunoreactivity. Therefore a primary role of microglia in PrP processing seem unlikely. Activated inicroglia may contribute to neuronal damage in CJD due to their cytotoxic potential.