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In vivo evidence for a non-T cell origin of interleukin-5
A G Castro1, R A Silva, P Minóprio
1Centro de Citologia Experimental, University of Porto, Portugal.
Abstract:
Eosinophil myelopoiesis is to a great extent regulated by interleukin (IL)-5. Analysis of IL-5 mRNA in spleen cell preparations by reverse transcription-polymerase chain reaction (RT-PCR) revealed the presence of message for this cytokine in uninfected severe combined immunodeficiency (SCID) mice. This message was increased following Mycobacterium avium infection. Normal BALB/c mice had higher levels of expression of IL-5 but the expression of this cytokine was reduced during M. avium infection. Anti-IL-5 monoclonal antibody administration in vivo to SCID mice reduced the number of peritoneal and splenic eosinophils. Gamma interferon (IFN-gamma) had an inhibitory effect of eosinophilopoiesis during infection of SCID mice by M. avium since neutralization of this cytokine increased the number of eosinophils detected in the peritoneal cavity of infected animals. Our results suggest that IL-5 may be produced by cells other than T cells that are both able to respond to infection and are under the control of IFN-gamma.
Insights
Interleukin-5 (IL-5) regulates eosinophil production. Mycobacterium avium infection alters IL-5 levels differently in SCID and normal mice, impacting eosinophil counts and suggesting non-T cell IL-5 production influenced by gamma interferon (IFN-gamma).
Area of Science:
- Immunology
- Cell Biology
- Infectious Diseases
Background:
- Eosinophil myelopoiesis is primarily controlled by interleukin-5 (IL-5).
- The role of IL-5 and other cytokines during Mycobacterium avium infection requires further elucidation, particularly in different immune contexts.
Purpose of the Study:
- To investigate the regulation of eosinophilopoiesis by IL-5 and gamma interferon (IFN-gamma) during Mycobacterium avium infection.
- To explore the cellular sources of IL-5 in response to infection.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT-PCR) to detect IL-5 mRNA.
- In vivo administration of anti-IL-5 monoclonal antibody.
- Infection of severe combined immunodeficiency (SCID) and BALB/c mice with Mycobacterium avium.
- Neutralization of IFN-gamma.
Main Results:
- IL-5 mRNA was detected in uninfected SCID mice and increased after M. avium infection.
- M. avium infection reduced IL-5 expression in normal BALB/c mice.
- Anti-IL-5 treatment decreased eosinophil numbers in SCID mice.
- IFN-gamma neutralization increased eosinophils in infected SCID mice, indicating an inhibitory role.
Conclusions:
- IL-5 plays a role in eosinophil production during M. avium infection.
- IFN-gamma inhibits eosinophilopoiesis in this model.
- Results suggest IL-5 may be produced by non-T cells responsive to infection and regulated by IFN-gamma.