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Mitogenicity of Naegleria fowleri extract for murine T lymphocytes
Abstract:
The whole-killed pathogenic free-living amoeba, Naegleria fowleri, contained mitogenic activity (NFM) for mouse spleen cells. Similar preparations from the non-pathogenic amoeba N. gruberi and the pathogenic Acanthamoeba culbertsoni lacked mitogenic activity. Fluids from N. fowleri cultures, containing amoeba antigens, also failed to cause proliferation of mouse spleen lymphocytes. Spleen cells from athymic nude mice failed to respond to NFM. In addition, nylon wool non-adherent, but not the adherent, spleen cell subpopulation proliferated in the presence of NFM. These results show that the factor(s) is mitogenic for T lymphocytes. The spleen cells from mice treated with cyclophosphamide doses known to deplete T suppressor cell activity from this organ failed to respond to NFM, indicating that NFM may be mitogenic for T suppressor cells.
Insights
Whole-killed pathogenic Naegleria fowleri contains a factor (NFM) that stimulates mouse spleen cells. This NFM is specifically mitogenic for T lymphocytes, potentially including T suppressor cells.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Naegleria fowleri is a pathogenic free-living amoeba.
- The immune response to Naegleria fowleri infection is not fully understood.
- Mitogenic factors can stimulate lymphocyte proliferation.
Purpose of the Study:
- To investigate the mitogenic activity of Naegleria fowleri.
- To determine which immune cells are affected by Naegleria fowleri mitogenic factors.
- To characterize the nature of the mitogenic activity.
Main Methods:
- Preparation of whole-killed Naegleria fowleri and culture fluids.
- Incubation of mouse spleen cells with prepared amoeba components.
- Assays for lymphocyte proliferation, including experiments with athymic nude mice and spleen cell subpopulations (nylon wool separation).
- Treatment of mice with cyclophosphamide to deplete T suppressor cells.
Main Results:
- Whole-killed Naegleria fowleri exhibited mitogenic activity (NFM) for mouse spleen cells.
- Preparations from non-pathogenic N. gruberi and pathogenic Acanthamoeba culbertsoni lacked mitogenic activity.
- Culture fluids containing amoeba antigens did not induce lymphocyte proliferation.
- Spleen cells from athymic nude mice did not respond to NFM.
- Nylon wool non-adherent spleen cells proliferated in response to NFM, indicating T lymphocyte mitogenicity.
- Spleen cells from cyclophosphamide-treated mice showed no response to NFM, suggesting NFM may be mitogenic for T suppressor cells.
Conclusions:
- Naegleria fowleri contains a specific mitogenic factor (NFM) for T lymphocytes.
- The mitogenic activity appears to be associated with the amoeba itself, not secreted antigens.
- NFM may preferentially stimulate T suppressor cells, warranting further investigation into its immunomodulatory role.