Solid Phase Antigen Luminescent Immunoassays (SPALT) for the Determination of Insulin, Insulin Antibodies and Gentamicin Levels in Human Serum

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Abstract
An interesting and novel alternative to conventional immunoassay techniques for the measurement of antigens and antibodies in body fluids is described. The label used for all assays is a pyruvate kinase-IgG conjugate of the relevant 2nd (species-specific) antibody. All assays follow the same principle in which a solid phase antigen is used to adsorb unreacted 1st (substance-specific) antibody following a conventional antibody-antigen reaction in a liquid phase. After washing, the solid phase antigen-1st antibody is allowed to react with the labeled 2nd antibody. The solid phase is then washed and the pyruvate kinase bound to the solid phase is used to generate ATP which is measured kinetically in a luminometer. Assays are described for insulin, insulin antibodies and gentamicin [an antibiotic] to demonstrate both the versatility and sensitivity of this type of assay. The insulin assay had a lower detection limit of < 0.25 .mu.U/tube and was comparable with the radioimmunoassay used for routine purposes both in sensitivity and reproductivity. The insulin antibody assay correlated well with the radiometric determination used routinely in the laboratory. The gentamicin assay correlated well with the routine commercial radioimmunoassay and also had comparable coefficients of variation. In all cases, the inter- and intra-assay variation was under 10% in the range of interest.