BackgroundA T-cell clone, thought to be the source of eosinophilopoietic cytokines, identified by clonal rearrangement of the T-cell receptor and by the presence of aberrant T-cell immunophenotype in peripheral blood defines lymphocytic variant of hypereosinophilic syndrome (L-HES). Design and MethodsPeripheral blood samples from 42 patients who satisfied the diagnostic criteria for HES were studied for T-cell receptor clonal rearrangement by polymerase chain reaction according to BIOMED-2. The T-cell immunophenotype population was assessed in peripheral blood by flow cytometry. The FIP1L1-PDGFRA fusion gene was detected by nested polymerase chain reaction. ResultsForty-two HES patients (18 males and 24 females) with a median age at diagnosis of 56 years (range 17-84) were examined in this study. Their median white blood cell count was 12.9×10 9 /L (range 5.3-121), with an absolute eosinophil count of 4.5×10 9 /L (range 1.5-99) and a median eosinophilic bone marrow infiltration of 30% (range 11-64). Among the 42 patients, clonal T-cell receptor rearrangements were detected in 18 patients (42.8%). Patients with T-cell receptor clonality included: T-cell receptor β in 15 patients (35%), Tcell receptor γ in 9 (21%) and T-cell receptor δ in 9 (21%) patients, respectively. Clonality was detected in all three T-cell receptor loci in 4 cases, in two loci in 7 patients and in one T-cell receptor locus in the remaining 7 patients. The FIP1L1-PDGFRA fusion transcript was absent in all but 2 patients with T-cell receptor clonality. Three patients out of 42 revealed an aberrant T-cell immunophenotype. In some patients, an abnormal CD4:CD8 ratio was demonstrated. ConclusionsT-cell abnormalities are present at high frequencies in patients with HES.

Idiopathic hypereosinophilic syndrome (IHES) is characterized by blood hypereosinophilia with no underlying cause and eosinophilia-associated organ dysfunction. Thirty-three patients, 20 female (61%) and 13 male (29%), with a median age of 56 years at diagnosis (range 16-77 years) were included in the study. The median blood eosinophilia at diagnosis was 7.6 × 10(9)/L and the median percentage of eosinophils in the bone marrow was 39.5%. The most common clinical manifestations were splenomegaly and cardiac involvement. Corticosteroids (CS) as monotherapy were initiated in all study patients. The median starting dose of prednisone was 30 mg daily (range 5-85 mg), and the maintenance dose varied from 5 mg twice weekly to 60 mg daily. Overall, 21 patients (64%) responded to CS within a week. Seven patients (21%) were resistant or intolerant to CS. Five patients (15%) achieved a 50% reduction of blood eosinophilia. In conclusion, CS were found to be highly effective in IHES with manageable side effects.

The term “hypereosinophilia of undetermined significance” (HEus) previously known as idiopathic, benign eosinophilia relates to patients who have a long-lasting, unexplained and asymptomatic blood HE. These patients have not been studied so far in terms of demographic characteristics and clinical outcome. The aim of this study was to present the clinical characteristics and outcome of HEus patients. This is a retrospective, single-center study of 40 patients with HEus. All patients underwent the basic and specialized evaluations in order to rule out the most common causes of blood HE, but no abnormalities were detected. Twelve patients with at least moderate blood hypereosinophilia (defined as greater than 3.0 × 109/L) for more than 1-year duration were treated with corticosteroids (CS) to avoid end-organ damage. Twenty-one patients (52 %) had an increased leukocyte count at diagnosis. Median blood eosinophilia was 4.2 × 109/L (range 1.5–55.4). HE > 3.0 × 109/L was demonstrated in 17 patients. 65 % of studied population had an increased serum IgE levels, whereas only 2 % demonstrated an increased serum vitamin B12 levels. A median bone marrow infiltration by eosinophils was 30.5 % (range 11–78.2). All treated patients responded promptly to CS and remained in complete remission while receiving low doses of CS (20 mg/day to 5 mg every 2-day). One patient developed hypereosinophilic syndrome (HES) after 11 years of follow-up. Further studies are needed to define risk factors of HES development. The use of CS for HEus patients is controversial and should be individualized.

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