Molecular characterization of the idiopathic hypereosinophilic syndrome (HES) in 35 French patients with normal conventional cytogenetics.

Idiopathic hypereosinophilic syndrome (HES) characterized by unexplained and persistent hypereosinophilia is heterogeneous and comprises several entities: a myeloproliferative form where myeloid lineages are involved with the interstitial chromosome 4q12 deletion leading to fusion between FIP1L1 and PDGFRA genes, the latter acquiring increased tyrosine kinase activity. And a lymphocytic variant, where hypereosinophilia is secondary to a primitive T lymphoid disorder demonstrated by the presence of a circulating T-cell clone. We performed molecular characterization of HES in 35 patients with normal karyotype by conventional cytogenetic analysis. TCRgamma gene rearrangements suggesting T clonality were seen in 11 (31%) patients, and FIP1L1-PDGFRA by RT-PCR in six (17%) of 35 patients, who showed no evidence of T-cell clonality. An elevated serum tryptase level was observed in FIP1L1-PDGFRA-positive patients responding to imatinib, whereas serum IL-5 levels were not elevated in T-cell associated hypereosinophilia. Sequencing FIP1L1-PDGFRA revealed scattered breakpoints in FIP1L1-exons (10-13), whereas breakpoints were restricted to exon 12 of PDGFRA. In the 29 patients without FIP1L1-PDGFRA, no activating mutation of PDGFRA/PDGFRB was detected; however; one patient responded to imatinib. FISH analysis of the 4q12 deletion was concordant with FIP1L1-PDGFRA RT-PCR data. Further investigation of the nature of FIP1L1-PDGFRA affected cells will improve the classification of HES.

Hypereosinophilia with abnormal T cells, trisomy 7 and elevated TARC serum level.

The idiopathic hypereosinophilic syndrome (HES) is a rare heterogeneous disorder, characterized by persistent blood eosinophilia with possible organ involvement. We describe here the case of a 20-year-old atopic male presenting chronic hypereosinophilia and eczema since childhood. Biological findings included hypereosinophilia (9.5 x 10(9)/L), hyperlymphocytosis (10.9 x 10(9)/L), polyclonal hypergammaglobulinemia and elevated IgE serum level. Flow cytometric analysis of blood lymphoid cells showed a population of CD2+CD3-CD4+TCRab-TCRgd- lymphocytes. These cells displayed a Th0/Th2 cytokine profile, and a clonal TCR rearrangement pattern. A high serum TARC level was observed. Karyotype studies on blood stimulated culture or lymph nodes revealed a cellular hyperdiploïd clone 47, XY, +7. To our knowledge, this chromosomal aberration has never been reported in such case.

[Investigation of chronic hypereosinophilia: new perspectives]. / Exploration des hyperéosinophilies chroniques: nouvelles perspectives.

In some circumstances and despite investigations, no aetiology is found for hypereosinophilia. This becomes of particular concern when hypereosinophilia is elevated and persistent. While some chronic hypereosinophilias signal the onset of malignant haemopathies, others remain unexplained for up to several years. But all may cause severe complications to the viscera, among which cardiopathies, and in particular endomyocardial fibrosis, are predominant. New data on chronic unexplained hypereosinophilia point to regulation defects in eosinophils or more often in T lymphocytes. Thanks to simple investigations such as flow cytometry, along with other more sophisticated procedures, we should soon be better equipped to classify chronic hypereosinophilia and, in the long term, to define more adequate strategies for treatment.

Estradiol-stimulated nitric oxide release in human granulocytes is dependent on intracellular calcium transients: evidence of a cell surface estrogen receptor.

We tested the hypothesis that estrogen acutely stimulates constitutive nitric oxide synthase activity in human granulocytes by acting on a cell surface estrogen receptor (ER). The release of nitric oxide was measured in real time with an amperometric probe. Exposure of granulocytes to 17beta-estradiol stimulated NO release within seconds in a concentration-dependent manner. The NO release was also stimulated by 17beta-estradiol conjugated to bovine serum albumin (E(2)-BSA), which suggests mediation by a cell surface receptor. Tamoxifen, an ER inhibitor, antagonized the action of both 17beta-estradiol and E(2)-BSA, whereas ICI 182,780, an inhibitor of the nuclear ER, had no effect. Using dual emission microfluorometry in a calcium-free medium, the 17beta-estradiol-stimulated release of NO from granulocytes was shown to be dependent on intracellular calcium ([Ca(2+)]i) transients in a tamoxifen-sensitive process. Exposure to BAPTA-AM (1,2bis-(-aminophenoxy)ethans-N,N,N', N'-tetraacetic acid tetra(acetoxyymethyl) ester), a [Ca(2+)]i chelator, reduced [Ca(2+)]i in response to E(2)-BSA, and depleting [Ca(2+)]i stores abolished the effect of 17beta-estradiol on NO release. Confocal photomicrographs using E(2)-BSA-FITC (fluorescein isothiocyanate) revealed cell membrane reactivity. Estrogen-stimulated NO release had an immunosuppressive effect, and it initiated granulocyte rounding and loss of adherence in a tamoxifen-sensitive manner. Finally, using reverse transcriptase-polymerase chain reaction, human neutrophil granulocytes expressed ERalpha but not ERbeta, suggesting that ERalpha may be the membrane receptor for 17beta-estradiol. The study demonstrated that a physiological dose of estrogen down-regulates granulocyte activity by acutely stimulating NO release via the activation of a cell surface ER which is coupled to increases in [Ca(2+)]i. (Blood. 2000;95:3951-3958)