Acid lysosomal hydrolases in systemic sclerosis and other connective tissue diseases

The activities of five lysosomal hydrolases were determined fluorometrically in the serum of patients with systemic sclerosis (PSS), systemic lupus erythematosus (SLE), dermatomyositis (DM), rheumatoid arthritis (RA), or Raynaud's disease (RD). In PSS the beta-galactosidase activity was significantly increased compared with controls and the other connective tissue diseases. The beta-N-acetyl-glucosaminidase was significantly increased in PSS, SLE and DM. In PSS both enzymes were more active in the early stage of the disease than later. These changes of enzyme pattern seem to be a relatively reliable marker for the differential diagnosis of PSS compared to other connective tissue diseases, especially for RD, in which the beta-galactosidase activity was significantly decreased. Further work is required to determine whether these polysaccharide-degrading acid hydrolases play a role in the pathogenesis of PSS.