CD3?CD4+ Lymphocytic Variant Hypereosinophilic Syndrome: Diagnostic Tools Revisited

Background Identification of patients with lymphocytic variant hypereosinophilic syndrome (L-HES) is challenging, and has important prognostic therapeutic implications. Objective This study was undertaken to assess diagnostic tools for L-HES develop evidence-based recommendations. Methods Biomarkers T-cell–driven disease were compared between versus idiopathic HES (I-HES) variants. Those performed routinely (serum immunoglobulin levels, T-cell phenotyping, receptor [TCR] gene rearrangement patterns) collected from medical files, whereas others prospectively assessed on stored blood samples CCL17/thymus activation regulated chemokine [TARC] in vitro cytokine production). Results included 48 I-HES 20 associated a CD3?CD4+ subset, including 7 less than 5% aberrant cells. Neither increased serum levels nor clonal TCR rearrangements sufficiently sensitive or specific L-HES. In contrast, systematically enhanced expression the surface antigens CD2, CD5, CD45RO, CD95 by these cells allowed accurate detection flow cytometry. Serum CCL17/TARC significantly higher in those I-HES, threshold 3000 pg/mL all subjects 75% specificity. Quantification intracytoplasmic production cytometry most reliable method type 2 expression, notably IL-4 IL-13. Conclusion Adapting standard procedure phenotyping unexplained hypereosinophilia currently means identifying