Impact of Echinococcus granulosus Cyst Fluid on the Phenotypic Dynamics and Degranulation of RBL-2H3 Mast Cells.

OBJECTIVE: This study aimed to evaluate the effects of Echinococcus granulosus cyst fluid (EgCF) on the phenotypic characteristics and degranulation activity of mast cells during echinococcosis-associated hypersensitivity reactions, using the RBL-2H3 rat basophilic leukemia cell line as an in vitro model. METHODS: The cytotoxic effects of EgCF on RBL-2H3 cells were assessed using the Cell Counting Kit-8 assay. Degranulation activity was quantified by measuring β-hexosaminidase release. Morphological alterations and cytoskeletal changes were evaluated via toluidine blue staining and phalloidin-labeled confocal laser scanning microscopy. Apoptotic cell populations were quantified using flow cytometry. RESULTS: EgCF at mass concentrations ranging from 0.5 to 5 mg/mL significantly enhanced cell proliferation. Higher EgCF concentrations were associated with increased morphological deformation, as evidenced by toluidine blue staining, and with significantly elevated β-hexosaminidase release compared to the control group (p < 0.01). Flow cytometry revealed a statistically significant increase in apoptosis rates in the treated groups (p < 0.01). Within 30 minutes of EgCF exposure, phalloidin staining showed notable cytoskeletal reorganization, including cellular wrinkling and pseudopodia extension. These morphological changes were partially reversed within 45 to 60 minutes. CONCLUSION: EgCF induces morphological transformation and promotes degranulation in mast cells, with the intensity of these responses correlating positively with EgCF concentration. These findings suggest a dose-dependent role of EgCF in modulating mast cell activity during parasitic hypersensitivity responses.