Impaired macrophage leishmanicidal activity at cutaneous temperature

Area of Science:

• Immunology
• Parasitology
• Dermatology

Background:

• Temperature significantly influences the pathogenesis of cutaneous leishmaniasis.
• Macrophage function is critical in controlling Leishmania infections.

Purpose of the Study:

• To measure the temperature of murine leishmanial lesions.
• To assess the leishmanicidal activity of lymphokine-activated macrophages at these temperatures.

Main Methods:

• Measurement of lesion temperatures in mice.
• In vitro assessment of macrophage leishmanicidal activity at varying temperatures.
• Evaluation of macrophage tumoricidal activity.

Main Results:

• Murine leishmanial lesion temperatures ranged from 27°C to 32°C.
• Lymphokine-activated macrophages showed reduced killing of Leishmania major at temperatures closer to those in vivo.
• Impaired microbicidal activity occurred even with non-replicating parasites.
• Macrophage tumoricidal activity was also depressed below 37°C.

Conclusions:

• Cutaneous temperatures impair macrophage microbicidal activity, potentially aiding parasite survival.
• Healing of leishmanial lesions may necessitate a robust local lymphokine response.