Eosinophil activation markers in clonal and non-clonal eosinophilia

Eosinophils are leukocytes with multiple functions in physiologic and pathologic circumstances. Eosinophilia is typically associated with reactive conditions (helmintic infections, allergic or drug reactions and atopic disorders) and sometimes with hematologic and non- hematologic malignancies. Evaluation of a patient with eosinophilia requires numerous imaging investigations and laboratory tests for establishing the right treatment. We measured the degree of eosinophilic activation using serologic biomarkers such as serum eosinophil cationic protein (ECP) , interleukin-5 (IL-5) and eosinophilic cationic protein/eosinophil count (ECP/Eo) ratio in order to differentiate earlier among distinct eosinophilic conditions: clonal, non-clonal with malignancy and reactive eosinophilia with inflammation. The median ECP value in eosinophilic patients was significantly higher when compared to that of the control group (19.55 vs. 4.93 ng/mL, p<0.05). Within patients with eosinophilia, the clonal eosinophilia group showed a significantly higher median ECP value compared to the median ECP values of the non-clonal eosinophilia groups - (30.15 vs. 19.5 ng/mL, p<0.05 and respectively 30.15 vs. 13.3 ng/mL, p<0.05). Also patients having non-clonal eosinophilia with malignancy had a significantly higher median ECP value compared to those of reactive eosinophilia and inflammation (19.5 vs. 13.3 ng/mL, p<0.05). While ECP serum levels seemed to be a discriminatory tool for different groups of eosinophilic patients IL-5 and ECP/Eo were less useful for this purpose. However our results must be confirmed in larger studies