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Regulatory T cells impede acute and long-term immunity to blood-stage malaria through CTLA-4
Journal article   Open access   Peer reviewed

Regulatory T cells impede acute and long-term immunity to blood-stage malaria through CTLA-4

Samarchith P Kurup, Nyamekye Obeng-Adjei, Scott M Anthony, Boubacar Traore, Ogobara K Doumbo, Noah S Butler, Peter D Crompton and John T Harty
Nature medicine, Vol.23(10), pp.1220-1225
10/2017
DOI: 10.1038/nm.4395
PMCID: PMC5649372
PMID: 28892065
url
https://www.ncbi.nlm.nih.gov/pmc/articles/5649372View
Open Access

Abstract

Malaria, caused by the protozoan Plasmodium, is a devastating mosquito-borne disease with the potential to affect nearly half the world's population. Despite mounting substantial T and B cell responses, humans fail to efficiently control blood-stage malaria or develop sterilizing immunity to reinfections. Although forkhead box P3 (FOXP3) CD4 regulatory T (T ) cells form a part of these responses, their influence remains disputed and their mode of action is unknown. Here we show that T cells expand in both humans and mice in blood-stage malaria and interfere with conventional T helper cell responses and follicular T helper (T )-B cell interactions in germinal centers. Mechanistically, T cells function in a critical temporal window to impede protective immunity through cytotoxic-T-lymphocyte-associated protein-4 (CTLA-4). Targeting T cells or CTLA-4 in this precise window accelerated parasite clearance and generated species-transcending immunity to blood-stage malaria in mice. Our study uncovers a critical mechanism of immunosuppression associated with blood-stage malaria that delays parasite clearance and prevents development of potent adaptive immunity to reinfection. These data also reveal a temporally discrete and potentially therapeutically amenable functional role for T cells and CTLA-4 in limiting antimalarial immunity.
Flow Cytometry Lymph Nodes - pathology Enzyme-Linked Immunosorbent Assay Parasitemia - immunology Germinal Center - immunology Humans Malaria - immunology Mice, Inbred C57BL Male CTLA-4 Antigen - immunology T-Lymphocytes, Regulatory - immunology Animals Immune Tolerance - immunology T-Lymphocytes, Helper-Inducer - immunology Mice Mice, Inbred BALB C Spleen - pathology

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