Plasma C1 inhibitor in malignant diseases: functional activity versus concentration.
Plasma C1 inhibitor (C1-INH) was determined in 64 patients with different malignant diseases and in 58 healthy persons. C1-INH antigen concentration was measured by radial immunodiffusion (RID), whereas its functional activity was assayed with chromogenic substrate. Within-run and day-to-day precision of both methods were good, with CVs ranging from 3.6 to 5.4%. Plasma C1-INH antigen concentrations were significantly higher in the patients than in healthy controls (P = 4.0 x 10(-3)), as were their C1-INH functional activities (P = 3.5 x 10(-3)). C1-INH activities obtained in the patient plasma samples were in correlation with their antigen concentrations (r = 0.914), showing that C1-INH synthesized in malignant disease was functional. However, the specific activity of the C1-INH (functional activity/antigen concentration ratio) was significantly lower in the patient group as compared with the controls (P = 2.1 x 10(-6)), indicating partial inactivation of plasma C1-INH in malignant diseases. The C1-INH specific activity in patients was inversely proportional to its antigen concentration.
Starcević
D
D
Clinical Chemistry Laboratory, University Clinical Centre, Belgrade, Yugoslavia.
Jelić-Ivanović
Z
Z
Kalimanovska
V
V
D002863:Chromogenic Compounds; D003174:Complement C1 Inactivator Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D005779:Immunodiffusion; D008297:Male; D009369:Neoplasms / Q000097:blood*; D015203:Reproducibility of Results
D002863:Chromogenic Compounds; D003174:Complement C1 Inactivator Proteins