UBIQUITINATED INCLUSIONS IN INCLUSION-BODY MYOSITIS PATIENTS ARE IMMUNOREACTIVE FOR CATHEPSIN-D BUT NOT BETA-AMYLOID

The nature of the inclusions in the human muscle disease inclusion-bod y myositis (IBM) has been the subject of debate. Parallels with Alzhei mer's disease have been drawn after these inclusions were found to be ubiquitinated, and immunoreactive with antibodies to beta-amyloid (alp ha beta) and certain amyloid-associated proteins. We have used a batte ry of antibodies against alpha beta and associated proteins to immunos tain muscle biopsies from patients with IBM. Although the inclusions a re ubiquitinated, we could not show immunoreactivity for alpha beta or the associated proteins investigated. We did, however, find that the ubiquitinated inclusions colocalised with the lysosomal marker, cathep sin D.