calcimycin and Hypereosinophilic-Syndrome

Eosinophils from patients with hypereosinophilic syndrome (HES) showed augmented release of leukotriene C4 (LTC4) by stimulation with A23187. In the present study, we investigated the involvement of cytosolic phospholipase A2 (cPLA2) in this phenomenon.. Eosinophils from normal and HES donors (2.5 x 10(6) cells/ml) were incubated with A23187 (0.03-3 microM) for 60 min in the presence or absence of a cPLA2 inhibitor, AACOCF3. The LTC4 released from eosinophils was measured by enzyme immunoassay. Distribution of cPLA2 and 5-lipoxygenase (5-LO) proteins within the eosinophils were detected by Western immunoblotting.. The level of LTC4 released from the HES eosinophils by stimulation with A23187 was higher than that from normal eosinophils. The A23187-induced LTC4 release was inhibited by AACOCF3 in a dose-dependent manner. The amounts of cPLA2 seemed to be increased in the non-stimulated HES eosinophils by an analysis of immunoblotting. To be noticed was that cPLA2 was detected as a phosphorylated and membrane-bound form in the HES eosinophils, but not in the normal eosinophils. In contrast, localization of 5-LO within the eosinophils under A23187 stimulation was not different between normal and HES donors, while the amounts of 5-LO also seemed to be increased in the HES eosinophils.. These results suggest that cPLA2, increased and activated (phosphorylated and membrane-translocated) in vivo, is involved in the augmented release of LTC4 from the HES eosinophils.

Topics: Arachidonate 5-Lipoxygenase; Blotting, Western; Calcimycin; Cell Membrane; Cytosol; Enzyme Activation; Eosinophils; Humans; Hypereosinophilic Syndrome; In Vitro Techniques; Leukotriene C4; Phospholipases A; Phospholipases A2

As the carbohydrate lacto-N-fucopentaose III (CD15 antigen or X-determinant) and its sialylated derivative sialyl-Lewis X are involved in the adhesion of cells rolling along the surface of endothelial cells, experiments were done to study the presence of these molecules on human eosinophils from patients with the idiopathic hypereosinophilic syndrome. Normal-density eosinophils from some patients showed higher levels of expression for lacto-N-fucopentaose III than light-density eosinophils. In contrast, sialyl-Lewis X was highly expressed by light-density eosinophils. Activation of normal-density eosinophils with calcium ionophore A23187 resulted in increased expression of these molecules for a short time. Monoclonal antibodies to these carbohydrates stimulated eosinophils to secrete eosinophil cationic protein, but not eosinophil peroxidase, and acted as costimulatory signals for C3b-induced degranulation of eosinophil cationic protein. It was suggested that CD15 and sialyl-Lewis X might contribute to eosinophil-mediated tissue injury in patients with the idiopathic hypereosinophilic syndrome.

Topics: Adult; Antibodies, Monoclonal; Blood Proteins; Calcimycin; Eosinophil Granule Proteins; Eosinophil Peroxidase; Eosinophils; Flow Cytometry; Humans; Hypereosinophilic Syndrome; Interleukin-5; Lewis X Antigen; N-Acetylneuraminic Acid; Peroxidase; Peroxidases; Respiratory Burst; Ribonucleases; Sialic Acids