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T-lymphocyte requirement for the induction of mouse macrophage procoagulant activity by Trypanosoma brucei
Abstract:
We have previously shown that peritoneal macrophages from Trypanosoma brucei infected mice, but not from uninfected mice, expressed high levels of procoagulant activity that could not be produced in vitro by incubation of unstimulated macrophages with bloodstream forms of trypanosomes. In the present study we demonstrate that trypanosome-induced macrophage activation can be achieved in vitro by providing either sensitized (day 7 of infection) lymphocytes and trypanosomes or the supernatant fluid from this interaction. The ability of lymphocytes to secrete macrophage-activating lymphokines is enhanced up to day 12 of infection but was absent in the later stages. Although enhancement of the procoagulant activity occurred in infected nude mice, it seems that macrophage function in African trypanosomiasis, as regards the expression of procoagulant activity, is regulated by T-lymphocytes.
Insights
African trypanosomiasis infection activates macrophages to express procoagulant activity. This activation in vitro requires lymphocytes and is regulated by T-lymphocytes, particularly early in infection.
Area of Science:
- Immunology
- Parasitology
- Cell Biology
Background:
- Peritoneal macrophages from Trypanosoma brucei infected mice exhibit high procoagulant activity.
- This activity could not be replicated in vitro by simply incubating macrophages with trypanosomes.
Purpose of the Study:
- To investigate the in vitro induction of trypanosome-induced macrophage activation.
- To determine the role of lymphocytes and lymphokines in this process.
- To elucidate the regulation of macrophage procoagulant activity during African trypanosomiasis.
Main Methods:
- In vitro co-culture of macrophages with trypanosomes, sensitized lymphocytes, and supernatant fluids.
- Assessment of macrophage procoagulant activity.
- Studies in infected nude mice to evaluate T-lymphocyte independence.
Main Results:
- Macrophage activation was achieved in vitro using sensitized lymphocytes and trypanosomes or their supernatant.
- Lymphocyte secretion of macrophage-activating lymphokines peaked around day 12 of infection and diminished later.
- Enhanced procoagulant activity was observed in infected nude mice, suggesting T-lymphocyte regulation.
Conclusions:
- T-lymphocytes are crucial regulators of macrophage procoagulant activity during African trypanosomiasis.
- Lymphocyte-derived factors mediate trypanosome-induced macrophage activation.
- The regulatory role of T-lymphocytes is stage-dependent during the infection.
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