Surface phenotype of clonal T cells from two hypereosinophilic patients. PBMC from two hypereosinophilic patients and from a healthy blood donor were stained with FITC-, PE-, or PerCP-conjugated MoAbs against CD4, CD3, CD2, CD28, CD45RO, CD25, CD7, and CD27 antigens. Flow cytometric determination of surface phenotype is shown after gating on CD4⁺ (healthy subject) or CD3⁻CD4⁺ (patients) lymphocytes. Data were obtained on more than 10,000 viable cells.