A rapid enzyme-linked immunosorbent assay for serum amyloid A using sequence-specific antibodies

A microtitre plate based enzyme-linked immunosorbent assay for determining the concentration of serum amyloid A (SAA) is described. The method employs easily produced sequence-specific rabbit antibodies and the preferential absorption of SAA to polystyrene, which obviates the use of capture antibodies and allows an assay time of only 3.5 h, so that the diagnostic potential of the SAA level as a rapid and reliable marker for inflammation can be fully exploited. The assay has a working concentration range of 0.1-2500 mg/L, which embraces the known biological variation of the SAA concentration. The intra-assay coefficient of variation (CV) for SAA concentrations above 10 mg/L is between 1.6 and 3.3% and the interassay CV between 3.0 and 4.2%. Recovery of SAA added to serum is from 96 to 102%.