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Leishmania major: excreted factor, calcium ions, and the survival of amastigotes
Abstract:
Mouse macrophages infected with amastigotes of Leishmania major contain about 40% more intracellular exchangeable calcium than control macrophages. Similar elevation of intracellular exchangeable calcium was observed in macrophages engulfing red blood cells coated with purified excreted factor from L. major. The rate of cytolysis of red blood cells coated with excreted factor was significantly lower than that of uncoated controls. Excreted factor strongly binds calcium; thus, the possible role of a microenvironment rich in calcium bound to excreted factor within the phagolysosome in protecting the amastigotes may be considered.
Insights
Leishmania major infection increases intracellular calcium in macrophages. The parasite's excreted factor binds calcium, potentially protecting amastigotes within a calcium-rich phagolysosome environment.
Area of Science:
- Immunology
- Parasitology
- Cell Biology
Background:
- Leishmania major infects macrophages, the primary host cells.
- Intracellular calcium is crucial for macrophage function and parasite survival.
Purpose of the Study:
- To investigate the effect of Leishmania major infection on intracellular calcium levels in mouse macrophages.
- To explore the role of Leishmania major excreted factor in calcium binding and its potential impact on parasite survival.
Main Methods:
- Measuring intracellular exchangeable calcium in infected and control mouse macrophages.
- Assessing the cytolysis rate of red blood cells coated with Leishmania major excreted factor.
- Evaluating the calcium-binding capacity of purified excreted factor.
Main Results:
- Macrophages infected with Leishmania major showed a 40% increase in intracellular exchangeable calcium compared to controls.
- Macrophages engulfing excreted factor-coated red blood cells also exhibited elevated intracellular calcium.
- Excreted factor demonstrated strong calcium-binding properties.
- Cytolysis of excreted factor-coated red blood cells was significantly reduced compared to uncoated controls.
Conclusions:
- Leishmania major infection leads to increased intracellular calcium in host macrophages.
- The excreted factor of Leishmania major binds calcium, potentially creating a calcium-rich microenvironment within the phagolysosome.
- This calcium-rich environment may contribute to the survival of Leishmania major amastigotes within macrophages.