This paper describes about measurement of Bβ 15-42 peptide derived from Bβ chain of fibrinogen or fibrin using a radioimmunoassay kit (IMCO). The Bβ 15-42 peptide was iodinated by chloramin T method, and the reaction mixture was passed through a Sephadex G-10 column. The yield of radioactivity was 68.3% with specific activity of 68μci/μg. This radioimunoassay system showed that coefficiency of variation was 7.7-11%, sensitivity was 0.16pmol/ml and recovery rate was 60.5%. The reactivity of Bβ 1-42 and fibrinogen with the antiserum to Bβ 15-42 was similar to that of Bβ 15-42. On the other hand, fibrinopeptide A and B showed no reactivity with the antiserum. When nomal plasma was incubated with urokinase in vitro, Bβ 15-42 immunoreactivity increased with a dependency on incubation time and dose of urokinase.
In 17 normal volunteers (male 8, female 9), values of Bβ 15-42 peptide were 0.30±0.56pmol/ml (mean±S. D.).
A patient with venous thrombosis who was treated with urokinase (48×104 IU/day) and dextran sulfate (3000mg/day) showed high levels of Bβ 15-42 peptide.
These results suggested that the measurement of plasma levels of Bβ 15-42 peptide was important to know the degrees of fibrino (geno) lysis in vivo, but was not possible to distinguish fibrinogenolysis from fibrinolysis.
