The choice of isolation technique for human peripheral blood eosinophils contributes to the understanding of clinically relevant data derived from in vitro research. Since the 1990s, eosinophils have been conventionally isolated via density gradient centrifugation followed by negative immunomagnetic selection using anti-CD16 antibody-coated magnetic beads. Due to recent advancements in molecular techniques, "newer" methods have been made commercially available that drastically reduce user handling and processing time while maintaining high population purity. Here, we describe an isolation procedure using one of these methods, the human MACSxpress® Whole Blood Isolation Kit, as well as outline protocols for differential staining and flow cytometry analysis to evaluate the purity and activation state of isolated cells. In addition, we highlight an in vitro degranulation assay that may be used to verify the intact functionality of the isolated eosinophils.
Keywords: Cytospin; Degranulation; Eosinophils; Flow cytometry; Immunomagnetic; Isolation; Negative selection; Population purity.