Differentiation of eosinophils from cord blood cell precursors: Kinetics of Fc epsilon RI and Fc epsilon RII expression

Expression of Fc epsilon RI and Fc epsilon RII/CD23 was examined by immunocytochemistry and flow cytometry on eosinophils differentiated from human cord blood cells in the presence of human interleukin-3 (rhIL-3), granulocyte/macrophage colony stimulating factor (rhGM-CSF) and interleukin-5 (rhIL-5) and on blood eosinophils purified from normal donors or patients with idiopathic hypereosinophilic syndrome (HES). On cord blood derived eosinophils, Fc epsilon RI expression started at 1 week of culture and increased to reach a plateau at 3 weeks of culture. Fc epsilon RII/CD23 appeared slightly later, after 2 weeks of culture, and the percentage of Fc epsilon RII/CD23-positive eosinophilic cells increased and stayed in plateau. Fc epsilon RI expression on cord blood derived eosinophils was downregulated after culture with interleukin-2 (rhIL-2), interleukin-4 (rhIL-4), rhIL-5, interferon-a (rhIFN-alpha), interferon-gamma (rhIFN-gamma). In contrast, the expression of Fc epsilon RII/CD23 on cord blood derived eosinophilic cells was upregulated after culture with rhIL-4 rhIL-5 and rhIFN-gamma, and downregulated with rhIL-2 and rhIFN-alpha. Fc epsilon RI was expressed on about 30% normal donor eosinophils as well as on normodense eosinophils from HES patients but significantly decreased on hypodense eosinophils. In contrast, Fc epsilon RII/CD23, expressed on a very small proportion of normal donor eosinophils, increased from normodense to hypodense eosinophils. These results suggest that Fc epsilon RI on eosinophils might represent one differentiation antigen expressed relatively early, with decreased expression through maturation or activation, whereas Fc epsilon RII/CD23 might rather be considered as a marl;er of eosinophil activation.