Published online before print November 13, 2008
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* Department of Immunology, Faculty of Medicine, Imperial College London, United Kingdom;
Department of Hematology, Oncology, and Rheumatology, University Hospital Heidelberg, Heidelberg, Germany; and
Department of Cellular Immunology, Max-Planck-Institute for Immunobiology, Freiburg, Germany
1 Correspondence: Imperial College London, Department of Immunology, Norfolk Place, London W2 1PG, UK. E-mail: p.kropf{at}imperial.ac.uk
The metabolism of the amino acid L-arginine is emerging as a crucial mechanism for the regulation of immune responses. Here, we characterized the impact of L-arginine deprivation on T cell and macrophage (M
) effector functions: We show that whereas L-arginine is required unconditionally for T cell activation, M
can up-regulate activation markers and produce cytokines and chemokines in the absence of L-arginine. Furthermore, we show that L-arginine deprivation does not affect the capacity of activated M
to up-regulate L-arginine-metabolizing enzymes such as inducible NO synthase and arginase 1. Thus, our results show that to exert their effector functions, T cells and M
have different requirements for L-arginine.
Key Words: arginase immune regulation t cell hyporesponsiveness iNOS cytokine chemokine