Expression pattern and cellular origin of cytokines in the normal and Toxoplasma gondii-infected murine brain

Am J Pathol. 1997 Mar;150(3):1021-35.


In the normal brain, low levels of cytokines are observed, whereas inflammatory disorders of the central nervous system are characterized by an up-regulation of cytokine production. The cellular sources for cytokines in the central nervous system are largely undefined. In the present study, we have analyzed intracerebral cytokine production in normal and Toxoplasma gondii-infected mice using immunohistochemistry, in situ hybridization, flow cytometry of brain-derived leukocytes, and reverse transcriptase polymerase chain reaction detection in various subpopulations of inflammatory cells. In the normal brain, neurons and choroid plexus epithelia expressed interleukin (IL)-1 beta and IL-10. Microglia/macrophages produced IL-1 beta, IL-10, and tumor necrosis factor-alpha In Toxoplasma encephalitis, these cell types exhibited increased levels of the respective cytokines. In addition, microglia/macrophages showed a de novo expression of inducible nitric oxide synthase. CD4+ and CD8+ T cells, which were recruited to the brain, produced IL-2, IL-10, tumor necrosis factor-alpha, and interferon-gamma. IL-4 was exclusively detectable in CD4+ T cells, whereas CD8+ T cells showed expression of IL-1 beta. As chronic Toxoplasma encephalitis was not associated with neuronal degeneration and an up-regulation of neurotrophic factors, some cytokines may also exert neurotrophic and/or neuroprotective properties.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Brain / cytology
  • Brain / metabolism*
  • Brain / parasitology
  • Cytokines / biosynthesis*
  • Cytokines / genetics
  • Encephalitis / metabolism*
  • Encephalitis / parasitology
  • Female
  • Flow Cytometry
  • Immunohistochemistry
  • Immunomagnetic Separation
  • Immunophenotyping
  • In Situ Hybridization
  • Lymphocyte Subsets / cytology
  • Lymphocyte Subsets / metabolism*
  • Lymphocyte Subsets / parasitology
  • Mice
  • Mice, Inbred BALB C
  • Nerve Growth Factors / metabolism
  • Polymerase Chain Reaction
  • RNA, Messenger / analysis
  • Toxoplasma / isolation & purification
  • Toxoplasmosis, Animal / metabolism*
  • Toxoplasmosis, Animal / pathology
  • Up-Regulation


  • Cytokines
  • Nerve Growth Factors
  • RNA, Messenger