[The total proteolytic and collagenolytic activity in the blood cells of patients with systemic scleroderma]

Collagenolytic (CA) and neutral caseinolytic activity (NCA) was studied in extracts from blood cells (neutrophils, mononuclear cells and platelets) of patients suffering from systemic scleroderma (SSD). 23 persons were examined. Of these, 15 had local skin lesions, 8 diffuse lesions. CA, both specific and per 10(6) cells was found to be dramatically decreased (2-4-fold) in all blood cells, whereas NCA was increased in neutrophils and mononuclear cells; in platelets, it remained within normal. The amount of protein in neutrophils and mononuclear cells was lowered 1.2 and 2-fold respectively. In diffuse skin lesions, the amount of protein in cells was lower than in local lesions. It should be noted that in SSD patients examined, the inflammatory process was unmarked. Therefore, the data on substantial changes in proteolytic activity cannot be related to the inflammatory process. A reverse correlation was established between CA in neutrophils and circulating immune complexes as was a reverse correlation between CA in mononuclear cells and blood antinuclear factor. The data presented indicate that proteinases are an important factor of the pathogenesis in SSD. Apparently, SSD is characterized not only by enhanced synthesis of collagen but also by a dramatic reduction of the activity of enzymes that specifically hydrolyze this group of proteins, which leads to a decrease of collagen catabolism and hence, to the development of fibrosis in tissues.