Strong immunoreactivity of alpha 1-antichymotrypsin co-localizes with beta-amyloid protein and ubiquitin in vacuolated muscle fibers of inclusion-body myositis.
In 10 of 10 inclusion-body myositis (IBM) patients, including 1 hereditary case, vacuolated muscle fibers contained large or small cytoplasmic inclusions immunoreactive for alpha 1-antichymotrypsin (alpha 1-ACT). All IBM muscle biopsies had characteristic cytoplasmic tubulo-filaments by electron microscopy. None of 17 control muscle biopsies contained the alpha 1-ACT immunoreactive inclusions characteristic of IBM. In vacuolated muscle fibers, alpha 1-ACT immunoreactive inclusions colocalized with beta-amyloid protein and ubiquitin immunoreactivities. Our study provides the first demonstration of alpha 1-ACT accumulations in abnormal human muscle, and it suggest that, as in Alzheimer's disease and Down's syndrome, alpha 1-ACT may be involved in the pathogenesis of IBM.
Bilak
M
M
Department of Neurology, University of Southern California School of Medicine, Los Angeles 90017.
Askanas
V
V
Engel
W K
WK
D000293:Adolescent; D000328:Adult; D000368:Aged; D016229:Amyloid beta-Peptides / Q000276:immunology*; D001921:Brain / Q000473:pathology; D002648:Child; D002918:Chymotrypsin / Q000276:immunology*; D003593:Cytoplasm / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D002479:Inclusion Bodies / Q000648:ultrastructure; D008854:Microscopy, Electron; D008875:Middle Aged; D009132:Muscles / Q000276:immunology / Q000473:pathology*; D009220:Myositis / Q000276:immunology / Q000473:pathology*; D014452:Ubiquitins / Q000276:immunology*
D016229:Amyloid beta-Peptides; D014452:Ubiquitins; D002918:Chymotrypsin