Korean J Parasitol.  2010 Dec;48(4):325-329. 10.3347/kjp.2010.48.4.325.

Suppression of CD4+ T-Cells in the Spleen of Mice Infected with Toxoplasma gondii KI-1 Tachyzoites

• Kim WH
• Shin EH
• Kim JL
• Yu SY
• Jung BK
• Chai JY

• KMID: 1104700
• DOI: http://doi.org/10.3347/kjp.2010.48.4.325

Abstract

Toxoplasma gondii KI-1, a recent new isolate from Korea, shows similar pathogenicity and infectivity to mice compared to the virulent RH strain. To understand characteristics of host immunity, including immune enhancement or suppression, we investigated proliferative responses and phenotypes of spleen cells. In addition, kinetics of IFN-gamma, a Th1 cytokine, was examined in BALB/c mice up to day 6 post-infection (PI). Intraperitoneal injection of mice with 103 KI-1 tachyzoites induced significant decreases (P < 0.05) in proliferative responses of spleen cells. This occurred at days 2-6 PI even when concanavalin A (con A) was added and when stimulated with KI-1 antigen, suggesting suppression of the immunity. CD4+ T-cells decreased markedly at day 2 PI (P < 0.05), whereas CD8+ T-cells, NK cells, and macrophages did not show significant changes, except a slight, but significant, increase of CD8+ T-cells at day 6 PI. The capacity of splenocytes to produce IFN-gamma by con A stimulation dropped significantly at days 2-6 PI. These results demonstrate that intraperitoneal injection of KI-1 tachyzoites can induce immunosuppression during the early stage of infection, as revealed by the decrease of CD4+ T-cells and IFN-gamma.

Keyword

Toxopalsma gondii; Korean Isolate-1 (KI-1 isolate); splenocyte (murine); intraperitoneal infection; IFN-gamma; host immunity

MeSH Terms

Animals
CD4-Positive T-Lymphocytes/*immunology
CD8-Positive T-Lymphocytes/immunology
Cell Proliferation
Female
*Immune Tolerance
Interferon-gamma/secretion
Killer Cells, Natural/immunology
Macrophages/immunology
Mice
Mice, Inbred BALB C
Spleen/*immunology
Toxoplasma/*immunology/*pathogenicity