A-BETA(40) IS A MAJOR FORM OF BETA-AMYLOID IN NONHUMAN-PRIMATES

Because aged nonhuman primates show beta-amyloid (A beta) deposition i n senile plaques and blood vessels similar to that seen in human aging and AD, we used C-terminal specific antibodies to A beta(40) and A be ta(42) to investigate A beta peptide length in the brains of 11 aged r hesus monkeys and a 59-year-old chimpanzee. In contrast to AD, where t he earliest and most prominent form of A beta in senile plaques is A b eta(42), in the monkey, A beta(40)-positive plaques predominated. The ratio of A beta(40):A beta(42)-positive plaques averaged 2.08 in the m onkey, as compared to a mean ratio of 0.37 in 68 human AD subjects (p < 0.001). A beta(40) was also more prominent in the chimpanzee than in humans. Possible explanations for these findings include species diff erences in the cleavage of A beta from the amyloid precursor protein o r in the activity of a putative carboxy peptidase forming A beta(40) f rom A beta(42) in situ. Copyright (C) 1996 Elsevier Science Inc.