Eosinophil granulocytes: functional differences of a new isolation kit compared to the isolation with anti-CD16-conjugated MicroBeads.

Background/purpose: Using a new eosinophil isolation kit, we were not able to confirm our previous findings of a delayed apoptosis of eosinophils in atopic dermatitis. Thus, we investigated whether this new isolation kit modulates the functional activity of eosinophils.
Methods: Peripheral blood eosinophils were isolated with the new isolation kit as well as conventionally with anti-CD16-conjugated MicroBeads. We analysed viability, apoptosis, CD69 and CD95 expression, streptavidin binding and superoxide anion release.
Results: Purity of eosinophils was higher using the new isolation kit (P < 0.05). However, these eosinophils had a decreased survival (P < 0.05-0.01), presented morphological features of apoptosis, showed an increased percentage of apoptotic nuclei (P < 0.01), an increased release of superoxide anions (P < 0.05), a higher expression of CD69 and CD95 (P < 0.05) and an increased binding to streptavidin compared to eosinophils isolated with anti-CD16 conjugated MicroBeads.
Conclusion: The new eosinophil isolation kit should not be used for the investigation of eosinophils as it potently affects their functional activity.