Inorganic pyrophosphatase-labelled enzyme immunoassay for beta 2-microglobulin

beta 2-Microglobulin was purified from human peritoneal dialysate by ultrafiltration, gel chromatography and DEAE-high performance chromatography. Anti-beta 2-monoclonal antibodies were developed in mice and a pair of the antibodies was utilized to develop an enzyme-linked immunosorbent assay (ELISA) kit for the analyte with utilizing a new enzyme label, inorganic pyrophosphatase (EC 3.6.1.1). The sensitivity of the assay was 0.6 microgram/l (3 x SD) and the assay was linear up to absorbance values of around 2.0. No hook effect occurred in any putative concentrations of beta 2-microglobulin in serum. The precision of the assay of one run varied within 5-7% CV and the interassay precision was 2.8-8.6% CV, while the recovery was 99.2 +/- 6.0%. Excellent correlation occurred against an established radioimmunoassay method. All the used reagents were storable for a minimum of 1 year at +4 degrees C. It was decided that inorganic pyrophosphatase is a label of choice for ELISA.