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[Eosinophil count in asthma. A marker of disease activity in intrinsic and extrinsic asthma]
1Medicinsk afdeling B, Rigshospitalet, København.
Insights
Blood eosinophil counts correlate with asthma severity and airway inflammation in children and young adults. Higher eosinophil levels indicate increased asthma symptoms and poorer lung function, suggesting they reflect overall asthmatic activity.
Area of Science:
- Allergy and Immunology
- Pulmonology
- Pediatric Medicine
Context:
- Asthma is a chronic respiratory disease characterized by airway inflammation and variable symptoms.
- Eosinophils are a type of white blood cell implicated in allergic inflammation.
- Understanding biomarkers for asthma activity is crucial for effective management.
Purpose:
- To investigate the correlation between peripheral blood eosinophil counts and key asthma parameters.
- To assess how eosinophil levels relate to respiratory symptoms, lung function, and airway hyperresponsiveness.
- To determine if this relationship holds true from childhood into early adulthood.
Summary:
- A longitudinal study followed 70 asthmatic individuals from childhood (age 10) to early adulthood (age 21).
- Direct correlations were observed between blood eosinophil counts and asthma symptom severity in both age groups.
- Inverse correlations were found between eosinophil counts and forced expiratory volume in 1 second (FEV1) percentage.
- In adulthood, eosinophil counts also correlated significantly with histamine responsiveness and diurnal peak expiratory flow (PEF) variation.
Impact:
- Peripheral eosinophil count serves as a valuable indicator of asthma activity and airway inflammation.
- These findings support the use of eosinophil counts in monitoring asthma severity and guiding treatment decisions.
- The study highlights the sustained relevance of eosinophil counts in assessing asthma control across different life stages.
Abstract:
The relationship between eosinophil count and pulmonary function (FEV1), respiratory symptoms, bronchial responsiveness to histamine and diurnal variation in peak expiratory flow rate (PEF) was studied in a group of asthmatics (n = 70) examined in childhood (mean age 10 yrs) and early adulthood (mean age 21 yrs), of whom 24 had intrinsic and 46 extrinsic asthma. Self-reported symptoms of asthma were graded on a scale from zero to five; histamine responsiveness was analysed by means of the dose-response slope (DRS). In both childhood and adulthood, a direct correlation was found between blood eosinophil count and symptom score (r = 0.69, p < 0.001 and r = 0.58, p < 0.001, respectively), whereas inverse correlations were observed between number of eosinophils and FEV1 expressed as percentage of predicted values (r = -0.75, p < 0.001 and r = -0.80, p < 0.001, respectively). Furthermore, in adulthood, eosinophil count was found to be significantly correlated to histamine responsiveness (logDRS) (r = 0.65, p < 0.001) and diurnal PEF variation (r = 0.81, p < 0.001); these correlations were also noted after dividing the subjects into intrinsic and extrinsic asthmatics. The findings in the present study suggest that the peripheral eosinophil count reflects asthmatic activity, and possibly the degree of inflammation in the airways, in both children and young adults.