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 im munocytochemistry and flow cytometry on eosinophils differentiated fro m human cord blood cells in the presence of human interleukin-3 (rhIL- 3), granulocyte/macrophage colony stimulating factor (rhGM-CSF) and in terleukin-5 (rhIL-5) and on blood eosinophils purified from normal don ors or patients with idiopathic hypereosinophilic syndrome (HES). On c ord blood derived eosinophils, Fc epsilon RI expression started at 1 w eek 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 cell s increased and stayed in plateau. Fc epsilon RI expression on cord bl ood derived eosinophils was downregulated after culture with interleuk in-2 (rhIL-2), interleukin-4 (rhIL-4), rhIL-5, interferon-a (rhIFN-alp ha), interferon-gamma (rhIFN-gamma). In contrast, the expression of Fc epsilon RII/CD23 on cord blood derived eosinophilic cells was upregul ated after culture with rhIL-4 rhIL-5 and rhIFN-gamma, and downregulat ed with rhIL-2 and rhIFN-alpha. Fc epsilon RI was expressed on about 3 0% 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 eosi nophils. These results suggest that Fc epsilon RI on eosinophils might represent one differentiation antigen expressed relatively early, wit h decreased expression through maturation or activation, whereas Fc ep silon RII/CD23 might rather be considered as a marl;er of eosinophil a ctivation.