期刊
INFECTION AND IMMUNITY
卷 83, 期 10, 页码 3816-3824出版社
AMER SOC MICROBIOLOGY
DOI: 10.1128/IAI.00446-15
关键词
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资金
- Centre National de la Recherche Scientifique (UMR CNRS 5164)
- French Research Agency [ANR-12-Blanc-GDSTRESS]
- Ligue Contre le Cancer (Comite de la Gironde)
- EviMalar European Community 7th Framework Program [242095]
- Wellcome Trust [REF 094752]
Malaria induces potent activation and expansion of the V gamma 9V delta 2 subpopulation of gamma delta T cells, which inhibit the Plasmodium falciparum blood cycle through soluble cytotoxic mediators, abrogating merozoite invasion capacity. Intraerythrocytic stages efficiently trigger V gamma 9V delta 2 T-cell activation and degranulation through poorly understood mechanisms. P. falciparum blood-stage extracts are known to contain phosphoantigens able to stimulate V gamma 9V delta 2 T cells, but how these are presented by intact infected red blood cells (iRBCs) remains elusive. Here we show that, unlike activation by phosphoantigen-expressing cells, V gamma 9V delta 2 T-cell activation by intact iRBCs is independent of butyrophilin expression by the iRBC, and contact with an intact iRBC is not required. Moreover, blood-stage culture supernatants proved to be as potent activators of V gamma 9V delta 2 T cells as iRBCs. Bioactivity in the microenvironment is attributable to phosphoantigens, as it is dependent on the parasite DOXP pathway, on V gamma 9V delta 2 TCR signaling, and on butyrophilin expression by V gamma 9V delta 2 T cells. Kinetic studies showed that the phosphoantigens were released at the end of the intraerythrocytic cycle at the time of parasite egress. We document exquisite sensitivity of V gamma 9V delta 2 T cells, which respond to a few thousand parasites. These data unravel a novel framework, whereby release of phosphoantigens into the extracellular milieu by sequestered parasites likely promotes activation of distant V gamma 9V delta 2 T cells that in turn exert remote antiparasitic functions.
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