Establishment of an assay method for human mast cell chymase.

Chymase secreted by mast cells found in fibroblast-containing interstitial connective tissue has been implicated in collagen fiber formation and extracellular matrix production. We established a method for determination of human chymase activity, and applied this technique to measurements in serum and liver tissue. The mean chymase concentration in liver biopsy specimens from 26 patients with chronic hepatitis was 5.23±5.98 ng/mg (ranges 0.32–21.4). The serum chymase concentration was below the limit of detection, in both chronic hepatitis patients and healthy individuals. No significant relationship was seen between chymase activity in liver tissue and severity of liver fibrosis, but further investigation in larger numbers of patients is warranted.