[Immunochemical determination of human thiol protein disulfide oxidoreductase in cell and tissue homogenates by competitive EIA].

Different monospecific antisera against thiol-protein disulfide oxidoreductase (TPO, EC 1.8.4.2, protein-disulfide isomerase, EC 5.3.4.1) were raised in rabbits by immunization with purified human TPO and characterized by means of Laurell and immunoblot techniques. A competitive anti-TPO-EIA with insolubilized TPO has been used to determine this enzyme in cells and tissue homogenates. The assay shows a sensitivity of 1.2 ng/ml and a specificity of about 99%. The TPO content in relation to the total protein was found to be: in pancreas 0.65%, liver 0.45%, spleen 0.12%, placenta 0.16%, tonsils 0.06% and lymph nodes 0.03%.