CEREBRAL VASCULAR AMYLOID DEPOSITION IN RABBITS WITH INDUCED THYROGLOBULIN IMMUNITY

Cerebral amyloid angiopathy (CAA) occurs in humans along with the neur itic amyloid plaques in Alzheimer's disease, in several familial (inhe rited) syndromes, and in a sporadic form that increases in prevalence with age to attain a rate of about 60% after age 90. In the non-Alzhei mer conditions, it is often accompanied by cerebral hemorrhage and som etimes also by dementia. We report here the experimental induction of cerebrovascular amyloid (CVA) in thyroglobulin (Tg)-immunized rabbits. The vascular deposits in these rabbits are comparable to that seen in humans in that they primarily involve arterioles, venules, and capill aries and exhibit microscopic and ultrastructural characteristics simi lar to the human lesion. Prominent congophilic vascular lesions in the brain were seen in three out of six Tg-immunized rabbits, whereas les s striking basement membrane thickening was evident in three other exp erimental animals, probably reflecting individual variations in vascul ar responses to actively induced Tg immunity. Occasional primitive amy loid plaques were also encountered adjacent to vascular lesions. These observations are of particular interest since in other experimental m odels, cerebral vascular amyloid deposits have not been observed, thus suggesting that immunopathogenic events induced by active Tg immuniza tion may be unique in their effects on the cerebral vasculature.