Different densities of human eosinophils respond differently to PAF and IL-5

Human eosinophils are heterogeneous, consisting of both normal and light density cells which may differ in their functional properties. In this study, we compared different densities of eosinophils in response to PAF and IL-5. The eosinophil activation markers were identified either by staining with monoclonal antibody EG2 or, by respiratory burst activity with dichrofluorescin diacetate (DCFH-DA). Both functions were analysed by flow cytometric analyzer. Results showed that light density eosinophils stained with a higher percentage of EG2 (EG2/ Kimura stain) in comparison with normal density eosinophils (88.5 +/- 19.1% vs. 43.9 +/- 18.5% p <0.01). When both groups of cells were analysed with the respiratory burst activity, on EG2+ cells, the activity in light density EG2+ cells were much higher than that of normal density EG2+ cells. These activities in both groups of cells can be further enchanced by PAF and IL-5. Furthermore, the light density EG2+ cells were more eligible to PAF and IL-5 stimulation than were normal density EG2+ cells. In conclusion, normal density and light density eosinophils had different respiratory burst activities; both groups of EG2+ eosinophils responded differently to PAF and IL-5.