Bio-rad Laboratories, Inc.

Paul F Wegfahrt

James F Monthony

Nathan Lewin

Karel Newman

Jane Schmidt

Methods are described for the development of monoclonal antibodies to intrinsic factor and the application of said antibodies in the development of B12 immunoassays. In particular, antibodies are described that are capable of binding to intrinsic factor only in the absence of vitamin B12, and that are released from binding in the presence, and upon the binding, of vitamin B12 to intrinsic factor. Assays may be formatted such that either antibody or intrinsic factor is immobilized or labeled.

Immunoassays for determining vitamin b12, and reagents and kits therefor

The method of this invention is characterized by the use of hydrolyzed cross-linked polyacrylamide particles to which have been bonded, by means of covalent bonds, antibiodies against the thyroid hormone to be determined. The particles selected are of a size which forms a stable hydrophyllic suspension. In the preferred embodiment a measured quantity of unextracted human serum is mixed together with a blocking agent in an amount sufficient to displace the thyroid hormone to be measured from thyroxine binding globulin (TBG), a radioactively labeled thyroid hormone of the type to be measured, and the antibody-polyacrylamide complex. The hormone to be measured is displaced by the blocking agent followed by the competitive binding of the labeled and unlabeled hormone to the antibody-polyacrylamide particles. The particles are readily separated from the sample liquid and the radioactivity of the particle material and/or in the liquid is determined. Particles containing Alcian yellow or blue dye facilitate practice of the method.

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Oakland, CA, United States of America

Paul F Wegfahrt