Parasites, Hosts and Diseases

The Korea Society for Parasitology and Tropical Medicine (대한기생충학·열대의학회)
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Cytokine and antibody responses of reactivated murine toxoplasmosis upon administration of dexamethasone

  • Kang Ki-Man (Department of Infection Biology, College of Medicine, Chungnam National University) ;
  • Choi In-Uk (Department of Infection Biology, College of Medicine, Chungnam National University) ;
  • Shin Dae-Whan (Department of Infection Biology, College of Medicine, Chungnam National University) ;
  • Lee Young-Ha (Department of Infection Biology, College of Medicine, Chungnam National University)
  • Published : 2006.09.01
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Abstract

Toxoplasma gondii has been shown to result in life-threatening encephalitis in immunocompromised patients after reactivation of dormant parasites. In order to obtain information on immune responses related to this phenomenon, BALB/c mice were infected with 25 cysts of the 76K strain of T. gondii, then, treated orally with dexamethasone (Toxo/Dexa-treated group) in order to reactivate the chronic toxoplasmosis. None of the T. gondii-infected mice died during the experimental periods, whereas the Toxo/Dexa-treated mice evidenced a significant attenuation of survival periods. Toxoplasma-specific IgG2a, IgA and IgM titers in sera were significantly depressed in the Toxo/Dexa-treated mice; however, the IgG1 sera titers were similar to those seen in the Toxoplasma-infected mice. The percentages of CD4+ and $CD8\alpha+$ T cells in the Toxo/Dexa-treated mice were significantly reduced 2 weeks after dexamethasone treatment. $IFN-\gamma$ and IL-10 production levels in the Toxo/Dexa-treated mice were depressed significantly, whereas IL-4 production was increased temporarily. The expression levels of the Toxoplasma-specific P30 and B1 genes were found to have been increased in the Toxo/Dexa-treated mice in comparison with the Toxoplasma-infected mice. Collectively, the findings of this study demonstrate that reactivation of murine toxoplasmosis as the result of dexamethasone treatment induced a depression in Th1 immune responses, whereas Th2 immune responses were not significantly influenced.

Keywords

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