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Arginase activity mediates reversible T cell hyporesponsiveness in human pregnancy
Complex regulation of T cell functions during pregnancy is required to ensure materno‐fetal tolerance. Here we reveal a novel pathway for the temporary suppression of maternal T cell responses in uncomplicated human pregnancies. Our results show that arginase activity is significantly increased in t...
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Published in: | European Journal of Immunology 2007-04, Vol.37 (4), p.935-945 |
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Main Authors: | , , , , , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Complex regulation of T cell functions during pregnancy is required to ensure materno‐fetal tolerance. Here we reveal a novel pathway for the temporary suppression of maternal T cell responses in uncomplicated human pregnancies. Our results show that arginase activity is significantly increased in the peripheral blood of pregnant women and remarkably high arginase activities are expressed in term placentae. High enzymatic activity results in high turnover of its substrate L‐arginine and concomitant reduction of this amino acid in the microenvironment. Amino acid deprivation is emerging as a regulatory pathway of lymphocyte responses and we assessed the consequences of this enhanced arginase activity on T cell responses. Arginase‐mediated L‐arginine depletion induces down‐regulation of CD3ζ, the main signalling chain of the TCR, and functional T cell hyporesponsiveness. Importantly, this arginase‐mediated T cell suppression was reversible, as inhibition of arginase activity or addition of exogenous L‐arginine restored CD3ζ chain expression and T cell proliferation. Thus, L‐arginine metabolism constitutes a novel physiological mechanism contributing to the temporary suppression of the maternal immune response during human pregnancy. |
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ISSN: | 0014-2980 1521-4141 1365-2567 |
DOI: | 10.1002/eji.200636542 |