Regulation of immune responses by L-arginine metabolism.
L-Arginine is an essential amino acid for birds and young mammals, and it is a conditionally essential amino acid for adult mammals, as it is important in situations in which requirements exceed production, such as pregnancy. Recent findings indicate that increased metabolism of L-arginine by myeloid cells can result in the impairment of lymphocyte responses to antigen during immune responses and tumour growth. Two enzymes that compete for L-arginine as a substrate - arginase and nitric-oxide synthase - are crucial components of this lymphocyte-suppression pathway, and the metabolic products of these enzymes are important moderators of T-cell function. This Review article focuses on the relevance of L-arginine metabolism by myeloid cells for immunity under physiological and pathological conditions.
Bronte
Vincenzo
V
Cancer Center of Veneto Region, Department of Oncological and Surgical Sciences, Padua University, Via Gattamelata 64, Padua, Italy. enzo.bronte@unipd.it
Zanovello
Paola
P
D000818:Animals; D001119:Arginase / Q000378:metabolism; D001120:Arginine / Q000378:metabolism*; D006801:Humans; D007111:Immunity, Cellular; D022423:Myeloid Cells / Q000201:enzymology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013491:Suppressor Factors, Immunologic / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology*
D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D013491:Suppressor Factors, Immunologic; D001120:Arginine; D019001:Nitric Oxide Synthase; D001119:Arginase