(A and B) Contaminating neutrophils within preparations of human eosinophils are leading to [Ca²⁺]_itransients. Spectrofluorometric measurements of [Ca²⁺]_i in Fura-2–loaded unprimed human eosinophils between 100% and 0% purity were performed. All contaminating cells were neutrophils as detected by flow cytometry. (A) Eosinophils contaminated with different percentages of neutrophils were stimulated with 100 ng/mL IL-8 and subsequently received 500 ng/mL eotaxin as a positive control. One representative experiment of five performed is shown. (B) Statistical analysis of [Ca²⁺]_i in human eosinophils contaminated with different amounts of purified human neutrophils (0% up to 100%). Cells were stimulated with 100 ng/mL IL-8 or 100 ng/mL eotaxin as a positive control. The results are presented as the mean ± SEM of five experiments.