Related Experiment Video
Updated: Jul 18, 2026
Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels
Published on: August 7, 2017
Induced sputum: validity of fluid-phase IL-5 measurement
M M Kelly1, R Leigh, P Horsewood
1Asthma Research Group, Departments of Medicine and Pathology, St Joseph's Hospital-McMaster University, Hamilton, Ontario, Canada.
Background:
IL-5 measurement in the fluid phase of induced sputum is considered to be important in the assessment of asthma, but the validity of these measurements is uncertain.
Objective:
We investigated the validity of sputum IL-5 measurements through a series of spiking experiments and examined the effect of dithiothreitol (DTT) on these measurements.
Methods:
Induced sputum from 26 asthmatic subjects was spiked with IL-5 and processed, and the percentage of recovery was measured by means of immunoassay. In 6 of the 26 samples the effect of adding albumin to the processing fluids was studied. In 3 separate samples radiolabeled IL-5 was added, and the recovery measured by means of gamma counting and immunoassay were compared. In addition, the effect of DTT on the immunoassay was examined.
Results:
The mean +/- SD recovery of spiked IL-5 was 26.1% +/- 14.6% measured by means of immunoassay; adding albumin increased the recovery to 47.7% +/- 8.0% (P <.001). The mean recovery measured by means of gamma counting was 84.8% +/- 5.7% (P <.001); adding albumin had no effect on recovery. DTT had no significant effect on IL-5 measurement.
Conclusion:
The validity of IL-5 measurement by means of current methods is poor. The discrepancy in recovery as measured by gamma counting compared with immunoassay suggests that there is a problem with the recognition of IL-5 epitopes by immunoassay in induced sputum. This cannot be attributed to DTT but may be due to other interfering substances present in sputum, such as sputum proteases, soluble receptors, or autoantibodies.
Related Concept Videos
01:26Sputum Studies I: Gram Stain, cytology, and Acid-fast smear and culture
Gram Stain
The Gram Stain is an integral part of sputum studies. It involves the staining of sputum, which permits...
01:20Sputum Studies II: Culture and Sensitivity
Sputum culture and sensitivity is a medical procedure used to diagnose bacterial infections in the respiratory tract and select the most appropriate antibiotics for treatment. This process involves analyzing sputum samples of thick and opaque secretions produced in the lungs and airways. These samples are collected from patients and then sent to the laboratory for analysis.
The test can identify various pathogens responsible for respiratory infections, including Streptococcus,...
01:25Pulmonary Function Tests
Pulmonary Function Tests are crucial diagnostic tools for assessing respiratory function, particularly in patients with chronic respiratory disorders. They comprehensively evaluate lung volumes, ventilatory function, breathing mechanics, diffusion, and gas exchange. These tests help diagnose pulmonary diseases and play a significant role in monitoring disease progression, evaluating disability, and assessing response to therapy.
PFTs involve using a spirometer, a...