Abstract
Anti-PM-Scl antibodies are most frequently found in patients with overlap syndrome of polymyositis and systemic sclerosis (31%), less frequently in myositis alone (8-11%), or systemic sclerosis (2%). Detection of these antibodies is associated with better outcome of the disease, which usually responds well to the treatment with low- to medium-dose glucocorticoids.
The human exosome is a PM-Scl autoantigen, a macromolecular complex of 11-16 polypeptides, which is involved in the degradation of precursor rRNA in the nucleolus and in the degradation of mature mRNA in the cytoplasm. Antibody response against the PM-Scl complex is primarily targeted against the PM-Scl-100 protein, the main epitope of which is PM1-alfa peptide.