Related Experiment Videos
Interleukin-6 production during chronic experimental infection
1Department of Microbiology, University of Melbourne, Parkville, Victoria, Australia.
Abstract:
The appearance of interleukin-6 (IL-6) in serum of mice was monitored during the course of chronic infection with either Brucella abortus vaccine strain 19 or a virulent Mycobacterium avium Complex (MAC) isolate. Serum IL-6 during brucella infection was higher than during infection with MAC, despite similar numbers of bacteria. Furthermore, IL-6 titres decreased after the peak of infection, falling to baseline levels before these chronic infections were eradicated. The ability of peritoneal cells or spleen cell suspensions to produce IL-6 under either specific or non-specific stimulus was greatly enhanced by infection. While production of IL-6 by these cultures was apparently mostly independent of T cells, T cells from infected mice could produce an IL-6 response. Thus CD4+ T lymphocytes prepared from mice which had recovered from B. abortus infection, cultured with antigen and antigen presenting cells, resulted in IL-6 production, which was not observed in similarly cultured CD8+ T cells, indicating a role for T cells.
Insights
Interleukin-6 (IL-6) levels varied during chronic Brucella and Mycobacterium avium Complex (MAC) infections in mice. Infected immune cells showed enhanced IL-6 production, with CD4+ T cells playing a key role.
Area of Science:
- Immunology
- Infectious Diseases
- Cytokine Research
Background:
- Chronic infections pose significant challenges to the immune system.
- Interleukin-6 (IL-6) is a key cytokine involved in immune responses.
- Understanding IL-6 dynamics during persistent infections is crucial.
Purpose of the Study:
- To investigate serum IL-6 profiles during chronic Brucella abortus and Mycobacterium avium Complex (MAC) infections in mice.
- To assess the impact of infection on IL-6 production by immune cells.
- To elucidate the role of T lymphocytes in IL-6 response during these infections.
Main Methods:
- Measurement of serum IL-6 levels in mice infected with Brucella abortus or MAC.
- Assessment of IL-6 production by peritoneal and spleen cell cultures.
- Isolation and culture of CD4+ and CD8+ T lymphocytes from infected mice for antigen-specific IL-6 response evaluation.
Main Results:
- Serum IL-6 was higher during Brucella infection compared to MAC infection, despite similar bacterial loads.
- IL-6 levels peaked and subsequently decreased before infection clearance.
- Infection enhanced IL-6 production by peritoneal and spleen cells, with CD4+ T cells from recovered mice demonstrating antigen-specific IL-6 production.
Conclusions:
- Distinct IL-6 profiles are observed during chronic Brucella and MAC infections.
- Infection significantly boosts the capacity of immune cells to produce IL-6.
- CD4+ T lymphocytes play a critical role in antigen-specific IL-6 production following Brucella abortus infection.