Eosinophil chemotactic activity in Leishmania amazonensis promastigotes

Area of Science:

• Parasitology
• Immunology
• Cell Biology

Background:

• Leishmania species are protozoan parasites responsible for leishmaniasis.
• Eosinophils play a role in immune responses, but their specific involvement in Leishmania infections is not fully understood.

Purpose of the Study:

• To investigate the role of eosinophils in the host response to Leishmania parasites.
• To determine if Leishmania parasites can directly attract eosinophils.

Main Methods:

• Mice were inoculated with living or lysed promastigotes of Leishmania amazonensis and other Leishmania species.
• Eosinophil infiltration was assessed in subcutaneous tissue and peritoneal fluid.
• Experiments were conducted using C5-deficient mice to evaluate complement-dependent mechanisms.
• In vitro chemotaxis assays were performed using purified eosinophils and Leishmania promastigote lysates.

Main Results:

• Tissue eosinophilia was observed in mice inoculated with Leishmania amazonensis promastigotes.
• Lysed promastigotes from five different Leishmania species induced eosinophil accumulation in the mouse peritoneum.
• Eosinophil infiltration occurred independently of complement.
• Induced eosinophils exhibited hypodensity, indicating cellular activation.
• Leishmania promastigote lysates demonstrated in vitro eosinophil chemotactic activity.

Conclusions:

• Leishmania parasites possess components that attract eosinophils.
• The chemotaxis of eosinophils by Leishmania is independent of the complement system.
• These findings suggest the presence of an eosinophil chemotactic factor within Leishmania parasites.