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An ultrastructural and cytochemical study of Tritrichomonas foetus-eosinophil interaction
1Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Brazil.
Abstract:
The fine structure of the process of interaction between uncoated and antibody-coated Tritrichomonas foetus with rat peritoneal eosinophils was studied. Eosinophils were purified by discontinuous Metrizamide gradient. Agglutination and immunofluorescence microscopy showed that T.foetus grown in a medium supplemented with different kinds of serum, antibodies present in it opsonize the parasites. Parasites incubated in the presence of anti-T.foetus rabbit serum attach to and are ingested by eosinophils. No such attachment was observed with trypsin-treated parasites. Attachment of antibody-coated parasites to the eosinophils induced their degranulation with the release of granule contents onto parasite surface causing its destruction. Hyperimmune serum was shown to be required for both attachment and ingestion of the parasites. The cytochemical localization of basic proteins and peroxidase showed that leucocyte granules fused with parasite-containing phagocytic vacuoles. Images were obtained suggesting that the binding of the parasites to the eosinophil surface triggers an exocytic process with release of the granule content onto the parasite surface.
Insights
Antibody-coated Tritrichomonas foetus parasites are ingested by rat eosinophils, triggering degranulation and parasite destruction. This interaction is crucial for opsonization and immune response against the protozoan parasite.
Area of Science:
- Immunology
- Parasitology
- Cell Biology
Background:
- Tritrichomonas foetus is a protozoan parasite that can cause disease.
- Eosinophils are a type of white blood cell involved in the immune response.
- The interaction between parasites and host immune cells is critical for pathogen clearance.
Purpose of the Study:
- To investigate the fine structure of the interaction between Tritrichomonas foetus and rat peritoneal eosinophils.
- To elucidate the role of antibodies in mediating this interaction.
- To understand the mechanisms of parasite opsonization and eosinophil degranulation.
Main Methods:
- Purification of rat peritoneal eosinophils using discontinuous Metrizamide gradient.
- Agglutination and immunofluorescence microscopy to observe parasite-eosinophil interactions.
- Incubation of parasites with specific antibodies and observation of attachment, ingestion, and degranulation.
Main Results:
- Antibodies opsonize T. foetus, facilitating attachment and ingestion by eosinophils.
- Attachment of antibody-coated parasites induces eosinophil degranulation.
- Eosinophil granules fuse with phagocytic vacuoles, releasing contents to destroy parasites.
- Hyperimmune serum is essential for both attachment and ingestion.
Conclusions:
- Antibody-mediated opsonization is critical for eosinophil recognition and phagocytosis of T. foetus.
- Eosinophil degranulation and release of granule contents are key mechanisms for parasite destruction.
- This study provides insights into the cellular and molecular mechanisms of anti-parasitic immunity.