Table 7.

Summary of asthma current biomarkers' characteristics.

Biomarkers in clinical use	Collection methods and advantages	Clinical practice application
Sputum eosinophils	Non invasive; Need of specialized equipment and trained staff; Not all samples can be adequate for processing	Provide a characterization of inflammatory status of the airways; Predicts responses to corticosteroids
Blood eosinophils	Minimal invasive; Easy to perform; Painful for some patients	One of criteria to define T2 high phenotype; Biomarker for the eligibility to anti-IL-5/anti-IL-5R treatment; Predict response to ICS and biologics (anti-IL-5/anti-IL-5R)
FeNO	Non invasive; User-friendly; Easy to collect	One of criteria to define T2 high phenotype; Describe the inflammatory status of the airways; Biomarker for the eligibility to anti IL-4R; Predict response to ICS and biologics
Serum IgE	Minimal invasive; Easy to perform, Painful for some patients	Biomarker for the eligibility to anti-IgE; Associated with specific sensitization to seasonal and perennial allergens; Associated with inflammatory, immunologic or hematologic disorders
Other biomarkers
Sputum neutrophils	Non invasive; Need of specialized equipment and trained staff; Not all samples can be adequate for processing	Provide a characterization of inflammatory status of the airways
Serum Periostin	Minimal invasive; Easy to perform; Painful for some patients	Predicts a greater airway obstruction and lung function decline, Predicts therapeutic responses to ICS
Blood neutrophils	Minimal invasive; Easy to perform; Painful for some patients	Associated with symptom control and asthma exacerbation
Sputum Cytokine	Non invasive; Need of specialized equipment and trained staff	Characterize the inflammatory phenotypes
VOCs	Non invasive	Identify inflammatory phenotypes

FeNO, fractional exhaled nitric oxide; ICS, inhaled corticosteroids; VOCs, volatile organic compounds.