Annals of Clinical Biochemistry > Volume 46, Number 5 > Pp. 401-406

This Article Figures Only Full Text Full Text (PDF) All Versions of this Article: acb.2009.008248v1 46/5/401    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Booth, C. K Articles by Ball, M. J PubMed PubMed Citation Social Bookmarking                      What's this?

Original Articles

Measurement of immunoglobulin A in saliva by particle-enhanced nephelometric immunoassay: sample collection, limits of quantitation, precision, stability and reference range

Christine K Booth¹, Dan B Dwyer², Paul F Pacque² and Madeleine J Ball²

¹ Human Protection & Performance Division, DSTO-Scottsdale, Tasmania; ² School of Human Life Sciences, University of Tasmania, Launceston, Tasmania, Australia

Corresponding author: Christine Booth PhD, P.O. Box 147, Scottsdale 7260 Tasmania, Australia. Email: christine.booth{at}defence.gov.au

Background: Total immunoglobulin A in saliva (s-IgA) is normally assayed using an enzyme-linked immunosorbent assay. We have investigated methodological issues relating to the use of particle-enhanced nephelometric immunoassay (PENIA) to measure s-IgA in whole unstimulated saliva and determine its reference range.

Methods: Whole unstimulated resting saliva was collected to determine sample stability (temperature, time, effect of a protease inhibitor), limit of quantitation (LOQ), assay precision and analytical variation. The reference range for 134 healthy adults was determined.

Results: Linearity was excellent (4–10.3 mg L^–1, P < 0.001; R² = 0.997) and without significant bias (mean of –0.7%). The lowest intra- and inter-analytical coefficients of variation were 1.8% and 7.5% and LOQ was 1.4 mg L^–1. The concentration of s-IgA is stable at room temperature for up to 6 h, at 4°C for 48 h, at –4°C for two weeks and at –80°C for up to 1.3 yr. There is no evidence that a protease inhibitor increases the stability or that repeated freeze–thawing cycles degrade sample quality. The reference ranges for s-IgA concentration, s-IgA secretion, s-IgA:albumin and s-IgA:osmolality were 15.9–414.5 mg L^–1, 7.2–234.9 µg min^–1, 0.4–19 and 0.6–8.9, respectively.

Conclusion: Automated PENIA assay of s-IgA is precise and accurate. High stability of collected saliva samples and the ease and speed of the assay make this an ideal method for use in athletic and military training situations. The convenience of measuring albumin and IgA on the same analytical platform adds to the practicability of the test.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?