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J Exp Med. 2016 Dec 12;213(13):3041-3056. Epub 2016 Nov 14.

Systemic toxoplasma infection triggers a long-term defect in the generation and function of naive T lymphocytes.

Author information

1
Immunobiology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892.
2
Experimental Transplantation and Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
3
T Cell Development Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892.
4
Biological Imaging, Research Technology Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892.
5
Laboratory of Immune Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
6
Immunology Section, Liver Diseases Branch, National Institute for Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
7
Immunobiology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 DJankovic@niaid.nih.gov ASher@niaid.nih.gov.

Abstract

Because antigen-stimulated naive T cells either die as effectors or enter the activated/memory pool, continuous egress of new T lymphocytes from thymus is essential for maintenance of peripheral immune homeostasis. Unexpectedly, we found that systemic infection with the protozoan Toxoplasma gondii triggers not only a transient increase in activated CD4+ Th1 cells but also a persistent decrease in the size of the naive CD4+ T lymphocyte pool. This immune defect is associated with decreased thymic output and parasite-induced destruction of the thymic epithelium, as well as disruption of the overall architecture of that primary lymphoid organ. Importantly, the resulting quantitative and qualitative deficiency in naive CD4+ T cells leads to an immunocompromised state that both promotes chronic toxoplasma infection and leads to decreased resistance to challenge with an unrelated pathogen. These findings reveal that systemic infectious agents, such as T. gondii, can induce long-term immune alterations associated with impaired thymic function. When accumulated during the lifetime of the host, such events, even when occurring at low magnitude, could be a contributing factor in immunological senescence.

PMID:
27849554
PMCID:
PMC5154934
DOI:
10.1084/jem.20151636
[Indexed for MEDLINE]
Free PMC Article

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