Immunoassay of alpha 1-acid glycoprotein in the Cobas Bio centrifugal analyzer.

Abstract

There is an increasing demand for quantification of serum alpha 1-acid glycoprotein (AAG, orosomucoid) in studies evaluating the protein binding of highly bound basic drugs. This paper describes an adaptation of an automated immunoturbidimetric assay for this protein to the Cobas Bio centrifugal analyzer. Replicate analyses of aliquots from six different solutions were used in determining precision. We also analyzed 367 patients' serum samples, in duplicate, to determine the distribution of AAG in hospitalized patients. The intra- and inter-run CVs ranged from 1.3% to 4.4% and from 0.6% to 6.6%, respectively. AAG concentrations in patients' samples ranged from 0.38 to 3.16 g/L. Results by this method correlate well with those by radial immunodiffusion, with no significant amount of bias between the two methods. This immunoturbidimetric procedure is faster and less expensive than currently used radial immunodiffusion techniques, and precision is acceptable.

Orosomucoid (α1-acid glycoprotein) plasma concentration and genetic variants: Effects on human immunodeficiency virus protease inhibitor clearance and cellular accumulation

“…The ORM concentration was measured spectrophotometrically at 340 nm by an end point immunoturbidimetry assay (DakoCytomation, Zug, Switzerland) on a Roche COBAS MIRA‐S analyzer (Roche Diagnostics, Lewes, United Kingdom) 39 by use of rabbit antihuman ORM antibody (No. Q 0326; Dako Diagnostics AG, Zug, Switzerland).…”

Mucoproteína versus alfa-1-glicoproteína ácida: o que quantificar?

“…Variabilidade analítica tão elevada quanto a observada na quantificação da Muco coloca este ensaio como semiquantitativo, minimizando sua utilidade clínica, em especial quando comparada com a performance da GPA. Marteau et al (7) e Verme et al (16) relatam, respectivamente, valores de 4,25% e 6,6% de coeficiente de variação interensaio para GPA em sistemas automatizados, semelhantes aos obtidos neste estudo (5,2%).…”

“…Os procedimentos analíticos em maior uso para a quantificação da GPA são a turbidimetria e a nefelometria, automatizadas, realizadas na presença de anticorpos específicos (2,4). As excelentes reprodutibilidade e confiabilidade destes procedimentos os têm recomendado para substituir a determinação da mucoproteína (7,16).…”