Respiratory syncytial virus replicates in human eosinophils. (A) Green fluorescent protein detected in eosinophils after challenge with rgRSV. Shown are (i) phase contrast, (ii) fluorescent, and (iii) composite of panels i and ii, showing expression of green protein in eosinophils. Photographed with 32× objective in 6-well culture dish in media. (B) Replication of RSV in human eosinophils. Cells were challenged with respiratory syncytial virus (RSV; MOI = 1) for 2 hours, washed, and resuspended, and total RNA was isolated immediately (day 0) or 4 days later for determination of virus copy number. Results are pooled data from 3 separate experiments, ***P < .001. (C) IL-6 is released by RSV-infected eosinophils. Detection of IL-6 by multiplex bead assay in culture supernatants from unchallenged (control), RSV-infected, and _hiRSV-challenged eosinophils. Each symbol represents an independent eosinophil donor; n = 3 to 4; *P < .02 and **P < .002. (D) Infectious virions are released from RSV-infected human eosinophils. Supernatants from human eosinophil cultures at 0 or 4 days after inoculation were used to challenge cells of the HEp-2 line, which is highly permissive for RSV replication. Total RNA from the HEp-2 cells was harvested at 7 days after inoculation, and Q-RT-PCR was performed to determine virus copy number. Results shown are a single experiment performed in triplicate, *P < .01. Data shown represent mean ± SEM.