DEVELOPMENT OF A NEW MICROPARTICLE-ENHANCED TURBIDIMETRIC ASSAY FOR C-REACTIVE PROTEIN WITH SUPERIOR FEATURES IN ANALYTICAL SENSITIVITY ANDDYNAMIC-RANGE

Novel assay techniques were applied to a newly developed microparticle -based assay for C-reactive protein (CRP). By using two different size d microparticles covalently coated with two monoclonal antibodies of d ifferent reactivity, high analytical sensitivity and a high upper meas uring limit could be simultaneously attained, resulting in a remarkabl y wide dynamic range. This range was further increased by calculating the signal (reaction rate) optimally with a new software capability of COBAS(R) INTEGRA, a clinical chemistry analyzer. The assay showed hig h precision between 2 mg/l and 160 mg/l with use of only 2.5 mu l spec imen. The detection limit was estimated as 0.3 mg/l CRP. The assay was four to eight times more sensitive and precise than existing turbidim etric or nephelometric assays with comparable upper measuring limits. The assay also showed good linearity and correlated well with commerci al assays. This new microparticle-based CRP assay provides the accurac y and precision that are required to determine CRP at low concentratio ns where new clinical implications such as prognosis of cardiovascular diseases are envisaged. The assay's wide dynamic range will additiona lly lead to a reduction in the number of repeated analyses, thus impro ving the efficiency of CRP determinations in clinical laboratories. (C ) 1998 Wiley-Liss, Inc.