Human inter-alpha trypsin inhibitor and immunologically related inhibitors investigated by quantitative...

The concentration in serum of inter-alpha trypsin inhibitor (I alpha I) and its immunologically related inhibitor, the prealbumin-like proteinase inhibitor (pA-PI), was investigated by quantitative crossed immunoelectrophoresis (CIE) in 33 healthy persons. The corresponding urinary excretion over a 4 h period of the immunologically related urinary proteinase inhibitor (UPI) was measured by rocket immunoelectrophoresis. The concentration of pA-PI increased significantly (p less than 0.001) with age whereas that of I alpha I and the urinary excretion of UPI were independent of age. There was no significantly difference in the concentration of the inhibitors in serum between the sexes, but females were found to have a lower urinary excretion of UPI than males (p less than 0.05). Furthermore we found no significant variation in the concentration of the inhibitors during the course of the day or from day to day over a 5 day period. Results obtained by rocket immunoelectrophoresis correlated well with enzymatically measured trypsin inhibitory activity.