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Expression of mRNA and immunoreactivity for the granulocyte/macrophage colony-stimulating factor in activated human
1Department of Allergy and Clinical Immunology, National Heart & Lung Institute, London, United Kingdom.
Abstract:
Using in situ hybridization, we have shown that activated human peripheral blood eosinophils express mRNA for granulocyte/macrophage colony-stimulating factor (GM-CSF). Between 15 and 27% of eosinophils gave positive hybridization signals for GM-CSF mRNA after stimulation with the calcium ionophore A23187 or interferon gamma, and 4 and 6% after incubation with interleukin 3 (IL-3) or IL-5. Activated eosinophils also gave specific immunoreactivity with an anti-GM-CSF polyclonal antibody, suggesting translation of the mRNA. These data indicate that eosinophils may be an important source of GM-CSF at sites of allergic inflammation. Furthermore, the identification of GM-CSF production by human eosinophils suggests that the pro-inflammatory potential of this cell type may be substantially greater than hitherto recognized.
Insights
Activated human eosinophils produce granulocyte/macrophage colony-stimulating factor (GM-CSF) mRNA and protein. This finding suggests eosinophils are a significant source of GM-CSF in allergic inflammation, potentially increasing their known pro-inflammatory role.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Eosinophils are key inflammatory cells in allergic diseases.
- The role of eosinophils in cytokine production is not fully understood.
Purpose of the Study:
- To investigate whether human eosinophils produce granulocyte/macrophage colony-stimulating factor (GM-CSF).
Main Methods:
- In situ hybridization was used to detect GM-CSF mRNA in activated human peripheral blood eosinophils.
- Immunoreactivity with an anti-GM-CSF antibody was assessed to confirm protein expression.
Main Results:
- Activated eosinophils expressed GM-CSF mRNA upon stimulation with calcium ionophore A23187 or interferon gamma (15-27%).
- Lower levels of GM-CSF mRNA were observed after stimulation with interleukin 3 (IL-3) or IL-5 (4-6%).
- Specific immunoreactivity for GM-CSF protein was detected, indicating successful mRNA translation.
Conclusions:
- Human eosinophils are a source of GM-CSF.
- Eosinophils may play a more significant role in allergic inflammation than previously recognized due to GM-CSF production.