Eosinophils may also play a role in tissue repair through secretion of fibroblast growth factor and transforming growth factor-β. These growth factors are secreted from the eosinophil following epithelial damage.13
A recent study found mean blood eosinophil levels in a healthy population (n=3641) to be 107 eosinophils/μL. The same study found blood eosinophil counts are consistently higher in males (120 cells/μL median) than females (100 cells/μL median), are highest in infancy and adolescence, and are independent of age in adults. Additionally, atopy, smoking, asthma, chronic obstructive pulmonary disease, obesity, and metabolic syndrome can be associated with higher eosinophil counts.16*
*Geometric mean; 95% confidence interval (105-110 eosinophils/μL).
Although eosinophils may contribute to overall health, the impact of levels
below what is considered normal is not known11
Cytokines and chemokines released from eosinophils lead to inflammation and tissue damage12,17,18