CD4 super(+)Foxp3 super(+) regulatory T cells mediate Toxoplasma gondii-induced T-cell suppression through an IL-2-related mechanism but independently of IL-10

• Published in: European journal of immunology Vol. 41; no. 12; pp. 3529 - 3541
• Main Authors: Tenorio, Eda P, Fernandez, Jacquelina, Castellanos, Carlos, Olguin, Jonadab E, Saavedra, Rafael
• Format: Journal Article
• Language: English
• Published: 01.12.2011
• Subjects: Toxoplasma gondii
• ISSN: 0014-2980; 1521-4141
• DOI: 10.1002/eji.201141507

Acute Toxoplasma gondii infection comprises an immunosuppression stage, characterized by a reduction in T-cell proliferation in vitro. Treg cells maintain the homeostasis of the immune system, but their role in T. gondii-induced suppression has not been addressed. We show herein that immunosuppression, affecting both CD4 super(+) and CD8 super(+) T-cell proliferation, concurs with a reduction in Treg-cell number. The residual Treg cells, however, are activated and display an increased suppressive capacity. We show that selective elimination of Treg cells using Foxp3 super(EGFP) mice leads to a full recovery of CD4 super(+) and CD8 super(+) T-cell proliferation. After Treg-cell removal, a reduced production of IL-10 was observed, but IL-2 levels were unchanged. The numbers of IL-10-producing Treg cells also increased during infection, although the in vitro neutralization of this cytokine did not modify T-cell proliferation, suggesting that IL-10 does not mediate the Treg-mediated suppression. However, addition of rIL-2 in vitro fully restored T-cell proliferation from infected animals. Thus, we show that Treg cells mediate the T-cell suppression observed during acute T. gondii infection through an IL-2-dependent mechanism. Our results provide novel insights into the regulation of the immune response against T. gondii.