Eosinophils and Major Basic Protein Damage but Do Not Detach Human Amniotic Epithelial Cells

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Abstract
Damage and detachment of epithelial cells is thought to contribute to the pathogenesis of asthma. Both eosinophils and neutrophils are found in asthmatic airways and several studies have suggested that eosinophils may be responsible for the epithelial cell detachment of asthma. To compare the capacity of purified human eosinophils and neutrophils to mediate epithelial cell detachment, we utilized a human amniotic epithelial cell-basement membrane model that we have recently described. Activated eosinophils induced little detachment at 4 h (< 10% detachment), which contrasted with that seen with equivalent numbers of identically handled neutrophils (29 ± 6% detachment, p < .05). In contrast, eosinophils did induce damage to epithelial cells to an extent similar to neutrophils when assessed using a Cr release assay (17 ± 6% and 18 ± 9% release of 51 Cr, respectively). When purified preparations of the major eosinophil-derived protein major basic protein (MBP) were studied, similar effects on epithelial cells were observed, i.e., damage (77 ± 13% release of 51Cr) without detachment (< 5% cell detachment). These data suggest that neutrophils are more effective in inducing detachment of human epithelial cells, whereas both eosinophils and neutrophils damage human epithelial cells