[About degradation products of the inter-alpha-trypsin inhibitor in serum. I. The inter-alpha-trypsin inhibitor as precursor of the acid stable trypsin-plasmin-inhibitor of the serum (author's transl)]. / Uber Abbauprodukte des Inter-alpha-Trypsininhibitors im Serum. I. Der Inter-alpha-Trypsininhibitor als Prekursor des säurestabilen Serum-Trypsin-Plasmin-Inhibitors

The humoral inter-alpha-trypsin inhibitor is to define as precursor of the acid stable trypsin-plasmin-inhibitor in the serum. The inhibitor is filtrated by the glomerulum and excreted in the urine. The serum level of the inhibitor is increased in nephropathy. Using a new assay for the intact precursor it was found that during inflammation the decreased precursor level indicates an increased turnover, though the glomerular filtration of the acid-stable inhibitor is within normal range. The increase of the precursor level during nephropathy indicates that the kidney is the main degradation organe for the inter-alpha-trypsin inhibitor. Nevertheless, an increase of the acid-stable inhibitor is to be seen. This fact is only to explain if it is assumed that the inter-alpha-trypsin inhibitor is permanently degraded everywhere in the organism.

[The inter-alpha-trypsin inhibitor as precursor of the acid-stable proteinase inhibitors in human serum and urine].

A small amount of antitryptic activity is detectable in the supernatant of deproteinized human serum. Preincubation of serum with trypsin causes an increase in acid-stable antitryptic activity. This rise in activity depends on the inter alpha-trypsin inhibitor concentration. The native inhibitor present in normal sera, and in higher concentrations in sera of patients with nephropathies, and the trypsin-liberated inhibitor show immunological cross reaction with antibodies to the serum inter-alpha-trypsin inhibitor. The two inhibitors differ in molecular weight and electrophoretic mobility. The physiological inhibitor (I-34), with a molecular weight of 34 000 and a high carbohydrate content, can be transformed by trypsin into an inhibitor (I-17) with a molecular weight of 17 000. This inhibitor is identical with the inhibitors liberated by trypsin from serum or from purified inter-alpha-trypsin inhibitor. The acid-stable inhibitor from urine is identical with the physiological serum inhibitor. Analogously, this inhibitor is transformed by trypsin into the inhibitor with a molecular weight of 17 000. We conclude that the inter-alpha-trypsin inhibitor is the precursor of both the physiological and the trypsin-liberated inhibitor. By a mechanism as yet unknown, but most likely a limited proteolysis, the secreted inhibitor is liberated from the high molecular weight precursor. In contrast to the monospecific trypsin-inhibiting precursor, the physiological and artificially liberated inhibitors are trypsin/chymotrypsin/plasmin inhibitors.

[Early recognition of a rejection crisis following kidney transplantation by determination of a low-molecular protease inhibitor in serum and urine]. / Frühzeitige Erkennung einer Abstossungskrise nach Nierentransplantation durch Bestimmung eines niedermolekularen Proteasen-Inhibitors im Serum und Harn

The dynamic of the lowmolecular acid stable inhibitor in serum and urine was investigated in 10 patients with kidney transplants. The same was done with serum creatinin levels. In kidney transplantation changing serum levels and excretion of acid stable proteinase inhibitors early indicate the starting function of the kidney transplant. Rapid reduction of the inhibitors serum level and massive excretion are sign of the functioning of the kidney transplant even though creatinin levels remain elevated. An increasing inhibitor concentration in serum indicates the beginning of a rejection crisis. This is an easy check-up which takes only a few minutes.