Studies on blood eosinophils. II. Patients with Löffler's cardiomyopathy

Area of Science:

• Cardiology
• Hematology
• Immunology

Background:

• Hypereosinophilic states, including Löffler's endocarditis and endomyocardial fibrosis, are characterized by elevated eosinophil counts.
• These conditions can lead to severe cardiac dysfunction, specifically restrictive cardiomyopathy.

Purpose of the Study:

• To investigate the characteristics of blood eosinophils in patients with heart failure and raised eosinophil counts.
• To explore the potential role of eosinophil degranulation in the pathogenesis of cardiac damage in these patients.

Main Methods:

• Analysis of blood eosinophils from four patients with elevated eosinophil counts and heart failure.
• Cardiological assessment including identification of endocardial lesions.
• Morphological and functional characterization of patient eosinophils compared to normal controls, including receptor expression and phagocytosis assays.

Main Results:

• Three patients exhibited endocardial lesions and restrictive cardiomyopathy consistent with Löffler's endocarditis or endomyocardial fibrosis.
• All patients had >1 X 10(9) eosinophils/L with vacuolated cytoplasm and altered crystalloid granules.
• Patient eosinophils displayed IgG and C3b receptors and phagocytic activity, unlike normal eosinophils.

Conclusions:

• Circulating eosinophils in these patients exhibited characteristics of mature or stimulated cells.
• These activated eosinophils underwent degranulation in response to blood-borne stimuli.
• The findings support the hypothesis that sustained release of eosinophil products contributes to the restrictive cardiomyopathy seen in hypereosinophilic states.