Inter-alpha-trypsin-inhibitor (ITI): use of immunoadsorbents for preparation of anti-ITI antiserum, ITI-free human serum and purified ITI

Substitution of carbonate by acetate buffer for IgG coating in sandwich ELISA

The first step of sandwich ELISA, namely adsorption of antibodies to plastic microtiter plates, was studied as a function of the pH of the coating buffer. Coating efficiency was assessed in terms of maximum signal (absorbance) observed in ELISA and also estimated by measuring the amount of functional antibodies adsorbed to the plate. While goat antibodies displayed better results after coating with acetate pH 5 buffer, rabbit IgGs generally worked well at pH 7.4. On average, the classical carbonate pH 9.6 buffer was only 50% as efficient.

Improvement of the sensitivity of mono- and bi-dimensional immunoelectrophoretic techniques by transfer onto nitrocellulose

The sensitivity of crossed immunoelectrophoresis (CIE) and rocket immunoelectrophoresis (RIE) does not usually permit the study of diluted protein solutions or the detection of trace components. Antigen-antibody precipitates obtained after immunoelectrophoresis were therefore dissociated and transferred from the agarose gel onto nitrocellulose filter by electrophoresis at pH 11. Immunochemical detection of proteins was then performed with the peroxidase-anti-peroxidase method. Diluted (1/100) solutions gave patterns similar to those obtained with the starting biological fluid. As an example, this technique was applied to human inter-alpha-trypsin inhibitor present at concentrations in the nanogram range. Other proteins, differing in charge and/or molecular weight, were also identified.

Quantitative study of human blood alpha-1-antitrypsin, alpha-2-macroglobulin and inter-alpha-trypsin-inhibitor with respect to plasma renin activity

Three blood protease inhibitors were immunochemically quantitated in normo- and hypertensive subjects divided according to their plasma renin activity. As inflammatory reactions could be suspected in many subjects, the inflammatory state was estimated on the basis of three acute phase reactants and allowed one to conclude that total inter-alpha-trypsin-inhibitor and inter-alpha-trypsin-inhibitor derivative, as well as alpha-1-antitrypsin levels were increased in inflammation. Involvement of either protease inhibitor tested in the control of plasma renin activity is unlikely as no relationship between plasma renin activity and protease inhibitor levels could be demonstrated in non-inflammatory conditions. Finally, there was no particular distribution of alpha-1-antitrypsin (PI) phenotypes in the overall population.

Inter-alpha-trypsin-inhibitor (ITI): two distinct mRNAs in baboon liver argue for a discrete synthesis of ITI and ITI derivatives

Human serum inter-alpha-trypsin-inhibitor (ITI) has so far been assumed to be comprised of a single polypeptide chain which can undergo fragmentation, whereby inhibitory ITI derivatives are released into the blood stream. In contrast, the analysis of the baboon liver mRNA translation products showed that ITI is made up of heavy and light chain(s). The latter may be excreted independently and very likely corresponds to the so-called ITI derivatives.

Inter-alpha-trypsin inhibitor (ITI): use of new antisera for qualitative studies and discrete quantitation of ITI and its derivatives

Inter-alpha-trypsin inhibitor (ITI) is a human protease inhibitor characterized by its coexistence with several physiological derivatives displaying immunological cross-reactivity when analyzed in plasma with usual anti-ITI antisera. Taking advantage of the presence in urine of a particular ITI derivative, antisera with restricted specificity for either ITI or its derivatives could be prepared. Some applications of these new reagents are given, including qualitative studies and discrete quantitation--by electroimmunoassay--of ITI and ITI derivatives. The procedures herein described should prove useful for qualitative and quantitative analysis to investigators dealing with mixtures of antigenically related proteins.

Isolation and characterization of an inter-alpha-trypsin inhibitor-IgG complex from human serum

Inter-alpha-trypsin inhibitor is a human serum protease inhibitor of Mr 180 000 which may release physiological derivatives. A complex between IgG and an inter-alpha-trypsin inhibitor derivative of Mr 30 000 has been recently detected in human serum and was found to be inactive against trypsin, in contrast with the known inhibitory activity of the free 30-kDa derivative. The present study deals with detailed characterization of an inter-alpha-trypsin inhibitor-IgG complex following its purification by affinity chromatography techniques (anti-inter-alpha-trypsin inhibitor immunoadsorbent and Protein A-Sepharose) in mild conditions. The resulting product reacted simultaneously with anti-IgG and anti-inter-alpha-trypsin inhibitor antibodies. This complex contained Mr 180 000 inhibitor at least to some extent. It migrated in the beta-gamma zone in agarose; its molecular weight was estimated to be 1 500 000 or more; part of it displayed covalent bonding between inter-alpha-trypsin inhibitor and IgG; it had a trypsin inhibitor activity. Immunoelectrophoresis allowed one to demonstrate the native complex in serum owing to the use of anti-inter-alpha-trypsin inhibitor and anti-gamma radioactively labelled antibodies. The double immunoreactivity thus evidenced proved to be heterogeneous with respect to its level and location in the native as well as in the purified complex.