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Multiplication of Leishmania in human macrophages in vitro
Abstract:
To facilitate in vitro studies of the immunology of human leishmaniasis, we developed a method of growing pathogenic Leishmania in human monocyte-derived macrophages. After 6 days of incubation, adherent mononuclear cells were infected with Leishmania donovani amastigotes obtained from infected hamster spleen cells or with L. tropica amastigotes obtained from infected BALB/c tissue mouse footpad. Forty-eight percent of the macrophages were initially infected, with a mean of 3.0 amastigotes per infected macrophage. After 6 days of incubation, 59% of macrophages were infected and contained 8.8 amastigotes per infected macrophage, representing 2.9-fold multiplication. Electron microscopy revealed the presence of dividing parasites within phagolysosomes. These observations indicate that Leishmania survive and multiply within human monocyte-derived macrophages despite fusion of secondary lysosomes with the parasitophorous vacuole.
Insights
Researchers developed a method to grow Leishmania parasites in human macrophages for immunology studies. This technique shows Leishmania can survive and multiply within these cells, aiding leishmaniasis research.
Area of Science:
- Immunology
- Parasitology
- Cell Biology
Background:
- Human leishmaniasis research requires effective in vitro models.
- Understanding parasite-host interactions is crucial for developing treatments.
Purpose of the Study:
- To establish a reliable method for culturing pathogenic Leishmania within human monocyte-derived macrophages.
- To investigate the survival and multiplication of Leishmania within these host cells.
Main Methods:
- Human peripheral blood mononuclear cells were differentiated into macrophages.
- Macrophages were infected with Leishmania donovani or Leishmania tropica amastigotes.
- Parasite load and multiplication were assessed over 6 days using microscopy and electron microscopy.
Main Results:
- An optimized method for infecting human macrophages with Leishmania was established.
- Initial infection rates reached 48%, with an average of 3.0 amastigotes per macrophage.
- After 6 days, infection increased to 59% with 8.8 amastigotes per macrophage, indicating a 2.9-fold multiplication.
- Electron microscopy confirmed parasite division within phagolysosomes.
Conclusions:
- Human monocyte-derived macrophages support the survival and multiplication of pathogenic Leishmania in vitro.
- Leishmania parasites can proliferate within macrophages despite lysosomal fusion events.
- This model system is valuable for studying the immunology of human leishmaniasis.