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Updated: Mar 16, 2026
Assessing the Cellular Immune Response of the Fruit Fly, Drosophila melanogaster, Using an In Vivo Phagocytosis Assay
Published on: April 10, 2019
Development of the Cellular Immune System of Drosophila Requires the Membrane Attack Complex/Perforin-Like Protein
Lauren Forbes-Beadle1, Tova Crossman2, Travis K Johnson1
1Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia.
Abstract:
Pore-forming members of the membrane attack complex/perforin-like (MACPF) protein superfamily perform well-characterized roles as mammalian immune effectors. For example, complement component 9 and perforin function to directly form pores in the membrane of Gram-negative pathogens or virally infected/transformed cells, respectively. In contrast, the only known MACPF protein in Drosophila melanogaster, Torso-like, plays crucial roles during development in embryo patterning and larval growth. Here, we report that in addition to these functions, Torso-like plays an important role in Drosophila immunity. However, in contrast to a hypothesized effector function in, for example, elimination of Gram-negative pathogens, we find that torso-like null mutants instead show increased susceptibility to certain Gram-positive pathogens such as Staphylococcus aureus and Enterococcus faecalis We further show that this deficit is due to a severely reduced number of circulating immune cells and, as a consequence, an impaired ability to phagocytose bacterial particles. Together these data suggest that Torso-like plays an important role in controlling the development of the Drosophila cellular immune system.
Insights
Torso-like, a protein in Drosophila, is crucial for immune cell development and combating Gram-positive bacterial infections. Null mutants exhibit reduced immune cell numbers and impaired phagocytosis.
Area of Science:
- Immunology
- Developmental Biology
- Cell Biology
Background:
- The membrane attack complex/perforin-like (MACPF) superfamily includes pore-forming proteins with immune effector roles in mammals.
- In Drosophila, Torso-like (Tsl) is known for developmental functions in embryo patterning and larval growth.
Purpose of the Study:
- To investigate the role of Torso-like in Drosophila immunity.
- To determine the specific immune mechanisms influenced by Torso-like.
Main Methods:
- Analysis of torso-like null mutants for susceptibility to bacterial pathogens.
- Quantification of circulating immune cells in wild-type and mutant flies.
- Assessment of phagocytic activity in immune cells.
Main Results:
- Torso-like null mutants show increased susceptibility to Gram-positive bacteria like Staphylococcus aureus and Enterococcus faecalis.
- Mutants exhibit a significant reduction in circulating immune cells.
- Impaired phagocytosis of bacterial particles was observed in torso-like mutants.
Conclusions:
- Torso-like plays a critical role in Drosophila immunity, distinct from typical MACPF effector functions.
- Torso-like is essential for the development and maintenance of the cellular immune system in Drosophila.
- The study highlights Torso-like's function in regulating immune cell numbers and phagocytic capacity.
