A method to preserve sputum for delayed examination

Multidisciplinary consensus on sputum induction biosafety during the COVID-19 pandemic

Sputum induction (SI) is the gold standard approach to the non-invasive study of airway inflammation. The differential count of inflammatory cells for SI allows patients with asthma to be classified according to inflammatory phenotypes and predicted therapeutic responses. Since SI involves the generation of aerosols, there is a need to establish a protocol to ensure biosafety in clinical practice during the current COVID-19 pandemic. The multidisciplinary consensus on SI described in this article was developed by 22 experts in SI from different Spanish hospitals who drew on available scientific evidence in achieving consensuated opinions, compiled by means of an electronic survey. We hope that these unified criteria and recommendations will guide health professionals in implementing SI sampling and processing procedures as safely as possible during the COVID-19 pandemic.

Airway inflammation, cough and athlete quality of life in elite female cross-country skiers: A longitudinal study

The aim of this study was to investigate the effect of a season of cross-country training and racing on airway inflammation, cough symptoms, and athlete quality of life in female skiers. Eighteen elite female skiers performed sputum induction and completed the Leicester Cough Questionnaire (LCQ) and the Recovery-Stress Questionnaire (REST-Q) at three time points (T1 - May/Jun, T2 - Oct/Nov, T3 - Jan-Mar) during the year. No changes were observed between T1 and T2. However, an increase in sputum eosinophils and lymphocytes (P < 0.05) and a significant change in all three domains of the LCQ were observed between T1 and T3 (P < 0.05). A significant association was found between the total yearly hours of training and the change in the total cell count (r(2)  = 0.74; P = 0.006), and a number of other sputum cell counts between T1 and T3. No changes were observed for any domain of the REST-Q. The results of this study demonstrate that airway inflammation and cough symptoms are significantly increased in elite female cross-country skiers across a year of training and racing. The increase in airway inflammation is related to the total amount of training and is worse during the winter months when athletes are training and racing in cold, dry air.

Establishing a normal range for induced sputum cell counts in Western Canada

BACKGROUND

Induced sputum cell counts are a noninvasive, reliable method for evaluating the presence, type and degree of airway inflammation. Whether current reference values for induced sputum cell counts are applicable in other induced-sputum laboratories, particularly those in Western Canada or at elevated altitude, is not clear.

OBJECTIVES

To describe the normal range of induced sputum cell counts in healthy adults in Western Canada.

METHODS

A total of 105 healthy nonsmoking adults with normal bronchial responsiveness and no history of lung disease proceeded with sputum induction. Sputum samples were fixed in formalin.

RESULTS

Sixty-nine subjects were included in the final analyses. The mean ± SD and median (interquartile range) of the cell counts, respectively, were: total cell count 2.453 ± 2.108, 2.000 (2.512); neutrophils 1.212 ± 1.491, 0.721 (1.016); eosinophils 0.034 ± 0.069, 0.005 (0.043); macrophages 1.050 ± 1.213, 0.696 (1.005); lymphocytes 0.057 ± 0.161, 0.001 (0.049); and bronchial epithelial cells 0.041 ± 0.126, 0.000 (0.027). The respective differential cell percentages were: neutrophils 50.3 ± 23.5, 51.9 (32); eosinophils 1.4 ± 2.3, 0.3 (2); macrophages 43 ± 22.8, 39.3 (32); lymphocytes 2.6 ± 5.2, 0.4 (2.5); and bronchial epithelial cells 2.2 ± 4.8, 0.0 (2.9). Bland-Altman analysis and intraclass correlation coefficients revealed excellent interobserver agreement for measurement of sputum cell types.

DISCUSSION

The range of induced sputum cell counts performed in a laboratory in Western Canada in healthy nonsmoking adult subjects was described; cellular distributions were similar to previous studies. This was also the first description of normal values for formalin-fixed induced sputum samples.

CONCLUSIONS

These results confirm that current reference values for induced sputum are generalizable across different laboratories, including those in Western Canada and those at elevated altitude, and are also generalizable to formalin-fixed samples, allowing use in the broader Canadian asthma population.

The impact of diurnal variation on induced sputum cell counts in healthy adults

BACKGROUND

Induced sputum cell counts are a non-invasive, reliable method for evaluating the presence, type, and degree of inflammation in the airways of the lungs. Current reference values for induced sputum cell counts in healthy adults do not account for the effects of circadian rhythm, including diurnal variation. The objective of this study was to describe the diurnal variation in induced sputum cell counts, compared between early morning and late afternoon, in healthy adult individuals.

METHODS

100 healthy adult subjects with no history of lung disease and normal bronchial reactivity proceeded with induced sputum testing at 7 am and 4 pm on different days. The order of testing was randomized. The cytotechnologist preparing and performing the cell counts was blinded to the sample collection time and subject characteristics.

RESULTS

65 subjects were included in the final analyses. There was no significant change in the total and differential sputum cell counts between the 7 am and 4 pm collections. There was good inter-observer agreement with respect to differential sputum cell count interpretation.

CONCLUSIONS

This is the largest study to assess the variation in induced sputum cell counts in healthy adult subjects at different times of the day. We found no significant change in total and differential sputum cell counts between the 7 am and 4 pm collection time points. This is in contrast to studies in asthmatics that demonstrated a circadian variation in sputum cell counts and other markers of inflammation, suggesting that fluctuations in airway inflammatory cells during the day are a disease-specific effect.

Clinical expert panel on monitoring potential lung toxicity of inhaled oligonucleotides: consensus points and recommendations

Oligonucleotides (ONs) are an emerging class of drugs being developed for the treatment of a wide variety of diseases including the treatment of respiratory diseases by the inhalation route. As a class, their toxicity on human lungs has not been fully characterized, and predictive toxicity biomarkers have not been identified. To that end, identification of sensitive methods and biomarkers that can detect toxicity in humans before any long term and/or irreversible side effects occur would be helpful. In light of the public's greater interests, the Inhalation Subcommittee of the Oligonucleotide Safety Working Group (OSWG) held expert panel discussions focusing on the potential toxicity of inhaled ONs and assessing the strengths and weaknesses of different monitoring techniques for use during the clinical evaluation of inhaled ON candidates. This white paper summarizes the key discussions and captures the panelists' perspectives and recommendations which, we propose, could be used as a framework to guide both industry and regulatory scientists in future clinical research to characterize and monitor the short and long term lung response to inhaled ONs.

Alcohol fixation of induced sputum samples for applications in rural communities

BACKGROUND

Sputum induction is a tool recommended for the assessment of airway inflammation and disease management. Currently, its use is limited because samples need to be processed within 3 h of induction (ie, while cells are viable); therefore, this procedure is unavailable to most clinicians.

OBJECTIVE

To develop a fixation method for induced sputum samples that allows for a delay in processing while maintaining sample integrity and not altering the standard processing method.

METHODS

Sputum samples were collected and split into three portions: a fresh sample processed using the routine method (within 3 h, using dithiothreitol); fixation in alcohol followed by delayed processing using the routine method (within 48 h to 72 h, using dithiothreitol); and fixation in formaldehyde followed by delayed processing using an alternative method (within 48 h to 72 h, using proteolysis). For each method, cytospins were prepared and differential cell counts were performed.

RESULTS

Fixation in alcohol provides accurate measures of eosinophils and macrophages, but not neutrophils. Formaldehyde fixation provides accurate measures of neutrophils and macrophages, but not eosinophils.

DISCUSSION

Alcohol fixation is a superior method for eosinophil quantification. It requires alteration of standardized methods for sputum sample processing and should be recommended for monitoring eosinophilic airway disease in settings where immediate processing of a sputum sample is not possible.

New interventions in asthma including bronchial thermoplasty

PURPOSE OF REVIEW

This article focuses on two novel asthma therapies - antibiotics and a procedure, bronchial thermoplasty. The challenges of identifying which treatment would best help an individual patient can be addressed by use of noninvasive measurements to define their asthma.

RECENT FINDINGS

Asthma is heterogeneous. Methods can be applied that define different phenotypes. We can now obtain a more detailed description of physiological changes, for example with bronchial provocation, and inflammatory changes, for example with exhaled nitric oxide or sputum cell analysis, in patients with airway symptoms. These measurements help define disease mechanisms and are especially informative when patients do not respond to standard therapy. Furthermore, detailed phenotyping may help identify who is most likely to benefit from newly developed, more specific therapies ranging from antagonists of individual mediators, for example anti-tumor necrosis factor-alpha or anti-immunoglobulin E, to interventions that directly address structural determinants of asthma, for example bronchial thermoplasty.

SUMMARY

Asthma treatment is evolving beyond the current cornerstones of bronchodilation, leukotriene antagonism and corticosteroids. This change will be propelled by a more detailed description of individual patients' disease that will enable customization of treatment, and the development of specific interventions that modify disease mechanisms, including airway remodelling.

Optimization of the conditions for preservation of induced sputum: influence of freezing on cellular analysis

BACKGROUND

Induced sputum (IS) analysis is a noninvasive, valid, and reproducible method for evaluating airway inflammation. It has been suggested that freezing of IS samples in order to delay analysis is feasible. However, the optimal conditions for preservation of IS samples have not been determined.

OBJECTIVES

To determine optimal freezing conditions of IS samples, ensuring adequate specimen quality for assessment of cell viability, total cell count, and differential cell count.

SUBJECTS AND METHODS

Twenty-one subjects were enrolled: 6 healthy control subjects, 5 patients with allergic rhinitis, 5 patients with mild asthma, and 5 patients with severe asthma. Each came to the laboratory once for IS sampling. Cell plugs were homogenized with dithiothreitol and separated into 12 aliquots. Viability and total and differential cell counts were determined for each aliquot. Bovine serum albumin (BSA) with dimethylsulfoxide (DMSO) was added to half of the aliquots, and fetal bovine serum (FBS) with DMSO was added to the other half. One half of the aliquots containing BSA or FBS were frozen at -20 degrees C, and the other half were frozen at - 80 degrees C. After 3, 7, or 10 days, samples were thawed and total cell counts, viability, and differential cell counts were assessed.

RESULTS

Slide quality and total cell counts did not vary significantly according to freezing duration, temperature, or medium when compared to nonfrozen control samples. With FBS at -80 degrees C, cell viability did not vary significantly between control samples and freezing for 3, 7, and 10 days (59% vs 54%, 59% vs 54%, and 58% vs 54%, respectively; p > 0.05), whereas every other condition showed a significant decrease. Freezing did not affect the eosinophil percentage significantly.

CONCLUSION

Freezing of IS samples in FBS with DMSO at - 80 degrees C allows adequate preservation of IS specimens. Samples can be kept for at least 10 days in those conditions without significantly altering total cell counts, viability, and eosinophil percentage.