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Figure 1: model for the eosinophil compartment in humans. Eosinophils are produced in the bone marrow and released into the blood as mature cells. Two separate differentiation paths seem to be present: one IL-5 dependent2 ,leading to inflammatory cells and one IL-5 independent7 ,leading to resident cells. In contrast to inflammatory cells, resident eosinophils are present in healthy individuals at rather stable numbers of ±100 cells/µl8.