The clonal Th2 cells present an activated memory phenotype.

PBMC from 2 hypereosinophilic patients (P1 and P2) and from healthy blood donors were stained with FITC-, PE-, or PerCP-conjugated mAbs against CD4, CD3, CD45RO, HLA-DR, and CD95 antigens. Surface phenotype was determined by flow cytometry after gating on CD3⁺CD4⁺ or CD45RO⁺ lymphocytes from healthy subjects and clonal CD3⁻CD4⁺ Th2 cells from both patients. The figure shows histograms from 1 experiment, representative of 3. The background staining using isotype-matched control Abs is represented by the broken line.