Study objectives: Eosinophils and neutrophils play major roles, respectively, in the pathogenesis of asthma and COPD, and it is well recognized that levels of these cells in peripheral blood are increased in relation to their pulmonary involvement. However, the relation between peripheral blood cell counts of the other major leukocyte groups and these lung diseases or markers of allergy or airflow obstruction is less clear. We have therefore investigated the association between peripheral blood levels of eosinophils, neutrophils, basophils, monocytes, and lymphocytes and the occurrence of chronic respiratory symptoms, atopy, lung function, and bronchial hyperresponsiveness, and the modifying effect of age, in adults.
Design: A cross-sectional general population study.
Setting: Data on > 2,000 British adults, who originally participated in a study of diet and lung health, were analyzed using multiple linear and logistic regression to adjust for potential confounders, including age, sex, and smoking history.
Results: We found that, like eosinophils, the peripheral basophil count was increased in relation to asthma and associated symptoms, and to airway hyperreactivity and increased total IgE, but differed from eosinophils in that basophils were unrelated to atopy. Monocytes were predominantly associated with symptoms indicative of obstructive airway disease, in similar relation to neutrophils, but both of these leukocyte counts were also increased in asthma patients in older age groups. Lymphocyte counts were unrelated to any objective or subjective marker of disease.
Conclusions: If peripheral blood cell counts reflect pulmonary involvement of these leukocyte groups, basophils and monocytes may play a distinct role in the pathogenesis of allergic and nonallergic respiratory disease.