Eosinophilia-associated Disorders Research Articles

Advances in the diagnosis and treatment of eosinophilia

Eosinophils play an important role in the pathogenesis of allergic, infectious and malignant diseases. Over the last decade, new diagnostic tools and treatment modalities have led to the re-evaluation of the existing definition of eosinophilic disorders. This review discusses a recent proposal for new terminology and classification of hypereosinophilia. The results of targeted therapy for hypereosinophilia-related disorders are also summarized. A panel of multidisciplinary experts agreed on unifying definitions and criteria of eosinophilia-associated disorders and created a new classification of hypereosinophilia-related conditions based on clinical, haematological and laboratory findings as well as the underlying cause of hypereosinophilia. Recent results of the treatment of idiopathic hypereosinophilic syndrome (HES) with the anti-interleukin 5 monoclonal antibody mepolizumab showed its efficacy and manageable safety profile. The treatment of platelet-derived growth factor alpha (PDGFRA)-positive HES with imatinib demonstrated long-lasting efficacy and low likelihood of drug resistance. The unifying terminology and definitions should aid physicians caring for patients with hypereosinophilia. Despite much progress, serum biomarkers correlate with disease severity and predict responses to treatment that are needed. There is also a great need for understanding and specific therapy for PDGFRA-negative HES.

Elevation of Soluble CD23 in Serum from Patients with Blood Eosinophilia

The levels of soluble CD23 (sCD23) were evaluated by a two-site immunoradiometric assay in the sera of 41 patients with eosinophilia-associated disorders and 20 normal subjects. We observed that, in the absence of treatment, sCD23 levels were elevated in patients with eosinophilia-associated Gleich's syndrome, IgA deficiency, T lymphoma or hypereosinophilic syndrome (HES), but not in patients with a parasitic infection. A significant reduction in the sCD23 levels was found after treatment, with a parallel decrease in eosinophil counts and in sCD25 levels, a marker of disease activity in HES. The lack of increase in membrane CD23+ B cells in eosinophilic patients together with the detection of sCD23 in eosinophil supernatants suggest that activated eosinophils present in eosinophilia-associated disorders can release soluble molecules cross-reacting with CD23. In conclusion, our results suggest that eosinophils themselves can represent one cellular source of sCD23. These findings are not only basic but also of clinical interest.

Synthesis of interleukin-5 by activated eosinophils in patients with eosinophilic heart diseases

Eosinophilic endomyocardial disease represents a major evolutive risk in chronic eosinophilia-associated disorders. Eosinophil granule proteins appear to be involved in cardiac injury, but the mechanisms leading to eosinophil infiltration and degranulation are not clear. Interleukin-5 (IL-5) has been recently shown to be produced by eosinophils and might play a role in both chemoattraction and degranulation of eosinophils. In four cases of eosinophilic diseases with severe cardiac failure, we evaluated the proportion of eosinophil phenotypes and the serum levels of eosinophil cationic protein (ECP) and soluble IL-2 receptor (sIL-2R), markers of disease activity in the hypereosinophilic syndromes. All four patients showed a markedly increased proportion of hypodense eosinophils with elevated serum ECP and sIL-2R levels. In all four patients, extracellular deposition of eosinophil granule proteins and features of eosinophil activation were observed in cardiac tissues. The synthesis of IL-5 by eosinophils was detected in myocardial sections and blood cells by in situ hybridization and by immunostaining with a monoclonal antibody against human IL-5. Sixty percent to 90% of tissue eosinophils expressed IL-5 mRNA and IL-5 protein. These data suggest that IL-5 can be produced by eosinophils at the sites of myocardial tissue damage and might participate in local eosinophil activation.

Synthesis of Interleukin-5 by Activated Eosinophils in Patients With Eosinophilic Heart Diseases

AbstractEosinophilic endomyocardial disease represents a major evolutive risk in chronic eosinophilia-associated disorders. Eosinophil granule proteins appear to be involved in cardiac injury, but the mechanisms leading to eosinophil infiltration and degranulation are not clear. Interleukin-5 (IL-5) has been recently shown to be produced by eosinophils and might play a role in both chemoattraction and degranulation of eosinophils. In four cases of eosinophilic diseases with severe cardiac failure, we evaluated the proportion of eosinophil phenotypes and the serum levels of eosinophil cationic protein (ECP) and soluble IL-2 receptor (slL-2R), markers of disease activity in the hypereosinophilic syndromes. All four patients showed a markedly increased proportion of hypodense eosinophils with elevated serum ECP and slL-2R levels. In all four patients, extracellular deposition of eosinophil granule proteins and features of eosinophil activation were observed in cardiac tissues. The synthesis of IL-5 by eosinophils was detected in myocardial sections and blood cells by in situ hybridization and by immunostaining with a monoclonal antibody against human IL-5. Sixty percent to 90% of tissue eosinophils expressed IL-5 mRNA and IL-5 protein. These data suggest that IL-5 can be produced by eosinophils at the sites of myocardial tissue damage and might participate in local eosinophil activation.