Damage to respiratory epithelium by guinea-pig eosinophils stimulated with IgG-coated Sepharose beads

Background There are no reports of respiratory epithelial damage induced by immunoglobulin-stimulated eosinophils. Objective We tried to induce damage to respiratory epithelium by guinea-pig (GP) eosinophils stimulated with guinea-pig IgG (GP-IgG)-coated Sepharose 4B beads. Methods GP tracheal epithelium was cultured together with GP eosinophils that had been collected from the peritoneal cavity, purified on a Percoll gradient, and stimulated with GP-IgG-coated beads (GP eosinophils:beads = 20 :1). Damage to the epithelium was observed with an inverted microscope. Results After 24 h of culture with three 10(6) eosinophils, irregularity of the surface of the epithelium, desquamation, shedding of cilia, and abnormal beating of cilia were observed. This damage was first observed after 12 h of incubation, and was more severe at 24 h. No damage was found when beads coated with human serum albumin (HSA) were used. GP eosinophils stimulated with GP-IgG released significantly more EPO than these stimulated with HSA, at 6 and 24 h. Heparin and catalase partially inhibited the epithelial damage. O-2-production by eosinophils was also enhanced with GP-IgG-coated beads. Conclusion Both granule basic proteins and reactive oxygen radicals may be responsible for epithelial damage, probably via an EPO + H2O2 + halide system. These results confirmed that stimulated eosinophils can damage respiratory epithelium.