Studies on immunological assay of vitamin K dependent factors. I. Measurement of factor VII antigen by radioimmunoassay.
A radioimmunoassay (RIA) for factor VII was developed using 125I-factor VII, anti-factor VII rabbit serum and anti-rabbit IgG goat serum. The lower limit of sensitivity in normal reference plasma was 3 X 10(-3) units/ml. Although the level of factor VII antigen (VII:Ag) in normal plasma samples (n = 20) 0.944 +/- 0.176 units/ml, correlated with that of factor VII coagulant activity (r = 0.89), VII:Ag level in paired normal sera showed a higher value (1.469 +/- 0.376 units/ml). The level of antigen according to RIA of factor VIIa activated by factor Xa increased 2.5-fold compared with that of unactivated factor VII. It is suggested that the polyclonal anti-factor VII produced in a rabbit had higher affinity for factor VIIa than for factor VII. In two out of seven patients with congenital factor VII deficiency, VII:Ag was detectable (0.04, 0.31 units/ml, respectively) whereas VII:C was less than 0.01 units/ml. In 12 warfarin-treated individuals, VII:C showed a lower level (0.121 +/- 0.063 units/ml) that that of VII:Ag (0.518 +/- 0.186 units/ml). During 4 weeks observation after stopping warfarin, VII:C and VII:Ag reached normal levels in 1 week. However, VII:C did not reach equivalence with VII:Ag until 4 weeks had elapsed.
D000818:Animals; D000941:Antigens / Q000032:analysis*; D005167:Factor VII / Q000032:analysis / Q000276:immunology* / Q000302:isolation & purification; D005168:Factor VII Deficiency / Q000276:immunology; D015942:Factor VIIa; D006041:Goats / Q000276:immunology; D006801:Humans; D007106:Immune Sera; D011817:Rabbits / Q000276:immunology; D011863:Radioimmunoassay / Q000379:methods*; D014859:Warfarin / Q000494:pharmacology
D000941:Antigens; D007106:Immune Sera; D014859:Warfarin; D005167:Factor VII; D015942:Factor VIIa