Induced sputum: Validity of fluid-phase IL-5 measurement

Kelly, Margaret M.; Leigh, Richard; Horsewood, Peter; Gleich, Gerald J.; Cox, Gerard; Hargreave, Frederick E.

doi:10.1067/mai.2000.106375

Cited by 28 publications

(21 citation statements)

References 29 publications

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“…To serve as a control for each spiked sample, 250 mL of PBS with 1% bovine serum albumin (BSA) was spiked with the same amount of IL-5. The authors have previously shown that adding exogenous IL-5 before or after dispersal with DTT has no effect on the recovery [11].…”

Section: Sputum Processingmentioning

confidence: 99%

“…Measurement of IL-5 is used to assess eosinophilic airway inflammation [8,9] and has recently become a target of drug therapy for asthma [7,8,10]. However, the authors have previously shown that the validity of IL-5 measurements in sputum by current methods is poor, with a mean¡SD recovery of spiked IL-5 of 26.1¡14.6% [11]. The reduced detection was due to poor recognition of IL-5 epitopes by immunoassay.…”

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confidence: 99%

“…Sputum from patients with inflammatory airways disease, including those with asthma, can have high proteolytic activity [11][12][13][14][15][16][17], with the majority of sputum proteases originating from sputum neutrophils [12,13]. These proteases are normally inhibited by complex formation with natural inhibitors present in sputum, such as a-1 proteinase inhibitor, antileukocyte protease (secretory leukocyte protease inhibitor) and a-2 macroglobulin [14,15].…”

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confidence: 99%

“…In addition, neutrophils possess protease-activated receptors, which, when bound by proteases, produce activation and degranulation of neutrophils [17] with further release of proteases. The authors have demonstrated that the IL-5 molecule remains intact after sputum processing [11], suggesting that the effects of proteases may be more subtle, possibly by the alteration of epitopes. It has also been shown that DTT does not interfere with the measurement of IL-5 by enzyme-linked immunosorbent assay (ELISA) [11].…”

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confidence: 99%

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Increased detection of interleukin-;5 in sputum by addition of protease inhibitors

et al. 2001

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The measurement of interleukin (IL)-5 in sputum is problematic, with interfering factors affecting immunoassay. The authors investigated whether sputum proteases could be acting as interfering factors by studying the effect of protease inhibitors (PI) on sputum IL-5 measurement.Induced sputa from 20 subjects with asthma were divided into aliquots, processed with and without protease inhibitors (in low and high concentrations) and the levels of IL-5 (spiked and endogenous) measured by enzyme immunoassay were compared.The concentration of sputum IL-5 was significantly increased by PI, with median (interquartile range) levels processed with no, low and high PI concentrations being 0 (0), 41.8 (75.6) and 66.1 (124.4) pg?mL -1 , respectively. There was also a significant increase in percentage recovery of spiked IL-5. Although high concentrations of PI reduced cell viability, there was no effect on total or differential cell counts and low concentrations of PI had no effect on cell counts or viability.Levels of endogenous interleukin-5 in sputum of asthmatic subjects can be significantly increased by the addition of protease inhibitors, and samples which would be regarded as negative for interleukin-5 without protease inhibitors may instead have considerable amounts of interleukin-5 detected.

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Section: Sputum Processingmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Increased detection of interleukin-;5 in sputum by addition of protease inhibitors

et al. 2001

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“…This is partially due to difficulties in standardization and assessment of normal values, which are based on variable dilution by saline or saliva. It may also be due to the potential interference between immunoassays or other detection procedures and the mucolytic agent dithiotreitol (DDT), proteases [7,8], and yet unknown formations of complexes between components of interest and, e.g. other proteins [9].…”

Section: Analysis Of Samplesmentioning

confidence: 99%

Noninvasive methods to measure airway inflammation: future considerations

et al. 2000

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This last contribution to the series focuses on open questions regarding: 1) methodological issues; and 2) the potential clinical application of the noninvasive methods such as induced sputum and the analysis of exhaled air for the assessment of airway inflammation. In addition their potential future role in occupational health and the early diagnosis of neoplastic lesions are briefly discussed. The future clinical application of noninvasive methods will depend on the progress made to improve their practicability, particularly in rendering them less time consuming and cheaper. To assess their clinical value, prospective studies are needed to establish whether patients actually benefit from the results obtained. This is also important to implement the methods into the healthcare system and to obtain adequate financial compensation. Therefore, it is necessary to know: 1) whether the assessment of airway inflam‐mation can aid in coming to an earlier and better defined diagnosis; 2) whether by repeated monitoring it is possible to avoid exacerbations through earlier interventions; and 3) whether the long‐term outcome of patients is improved through knowledge of the type and degree of airway inflammation that is taken into account in selecting the appropriate treatment. In the meantime a wealth of data has become available, both for induced sputum and the analysis of exhaled air, which give these methods the potential to be incorporated into future clinical practice. This, however, will, amongst the other issues, depend on favourable cost‐benefit ratios which should also be the subject of future prospective studies.

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