Plasma kininogen concentration: the low level in cord blood plasma and age dependence in adults.

Antigenic concentration of total kininogen, kinin liberated in vitro, and the antigenic concentration of high molecular weight (HMW) kininogen was measured in 58 different samples of cord blood plasma and in plasma samples from 67 healthy blood donors. Total kininogen and kinin concentration in cord blood plasma was more than twice as low as in pooled plasma of adult persons, and the concentration of HMW-kininogen in cord blood plasma was close to one-third of normal. The concentration of total kininogen and of HMW-kininogen increased with age in adults. All these findings were highly statistically significant.