Spatial relationship of AMY protein deposits and different species of A beta peptides in amyloid plaques of the Alzheimer disease brain

To further define the spatial relationship of "AMY" plaques detected by ant ibodies to an unidentified 100 kD AMY protein and amyloid plaques in Alzhei mer disease (AD) brains, double immunofluorescence studies were performed w ith an anti-AMY antibody and a panel of antibodies to different species of A beta peptides. We report substantial colocalization of AMY immunoreactive plaques with amyloid plaques labeled by antibodies to species of A beta st arting at position 3 with a pyroglutamate modified glutamic acid, however A MY immunoreactive deposits colocalized to a lesser degree with amyloid plaq ues labeled by antibodies to other variants of the A beta peptide. Moreover , different immunohistochemical parameters influenced the extent to which c olocalization of AMY deposits and A beta immunoreactive plaques was demonst rable. We conclude that deposits of distinct species of A beta peptides dif ferentially colocalize with one another and with AMY plaques in the AD brai n.