Time course of RANTES, EPO, and β-hexosaminidase release from human peripheral blood eosinophils induced by 500 U/mL recombinant human IFN-γ. (A) RANTES immunoreactivity in supernatants of stimulated eosinophils (2 × 106 cells/time point) was detected using a specific ELISA. Values represent averages of triplicate measurements from cells at 0, 10, 30, 60, 120, and 240 minutes of incubation obtained from a representative donor. A similar trend of release was observed in four separate donors. The dotted line represents a single measurement of spontaneous release of RANTES from eosinophils (duplicate values given for times 0 and 60 minutes). *P < .05 compared with RANTES measured in supernatants at the start of the time course by Kruskal-Wallis one-way analysis of variance. The detection sensitivity of the RANTES ELISA was 31.2 pg/mL. (B) IFN-γ also induced the release of eosinophil peroxidase and another granule-stored product, β-hexosaminidase, detected in the same IFN-γ–stimulated supernatants shown in (A). The amount of granule protein release is expressed as a percentage of the release induced by a maximally stimulating agonist (serum-coated Sephadex beads) in another sample. Points and error bars represent the mean and standard error of mean (SEM) of at least three measurements.
