Circulating eosinophil colony-forming cells in pure eosinophil aplasia

Using a methylcellulose clonal culture method, we found eosinophil colony-forming cells in the blood of two patients: a 46-year-old white woman with a long history of urticaria and allergic rhinitis and complete absence of eosinophils secondary to IgG-mediated and complement-mediated destruction of her eosinophils; and a white woman with a history of allergic rhinitis and asthma and a complete absence of eosinophils in her peripheral blood. Addition of the patients' plasma or IgG to cultures of peripheral blood mononuclear cells derived from normal persons or the patients inhibited formation of eosinophil colonies without influencing colony formation in other hemopoietic cell lineages. In contrast, normal plasma or IgG had no effect on the formation of eosinophil colonies. That the IgG-mediated cytotoxic activity of eosinophils prevents the expression of an apparently normal eosinophilopoietic potential suggests an autoimmune basis for the eosinophil aplasia.