Background and aims A growing number of diseases (trauma, certain cancer, and certain infection) in humans appear to be associated with L-arginine deficiency. In condition of L-arginine depletion, T-cell proliferation is impaired. In mice model, certain Th2 conditions were shown to activate arginase and lead to L-arginine depletion. However, the modulation effects of L-arginine towards T-cells immune polarisation and regulation are not understood.
Methods To investigate the different modulation effects of L-arginine on neonatal and adult lymphocyte polarisation, the cytokines produced by cord blood mononuclear cells (CBMC) and adult peripheral blood mononuclear cells (PBMC) at indicated L-arginine were determined.
Results CBMC produced less Th1 but higher Th2 cytokines than PBMC. Both adult and neonate T cells cannot produce IFN-γ efficiently in the absence of L-arginine. But high IL-4 and low IL-13 were produced by CBMC in L-arginine free condition. About the Th3 cytokines, CBMC produced lower TGF-β but higher IL-10 than PBMC. L-arginine levels had no influence on the TGF-β production (PBMC and CBMC). L-arginine enhanced the IL-10 production of CBMC. CBMC showed higher proportion of CD4+CD25+ cells and higher Foxp-3 expressions with L-arginine rich condition.
Conclusions These results suggested that L-arginine modulate neonatal T-cells polarisation may partially through the IL-10 producing Tr1 cells mechanism. Understanding the biological role played by L-arginine deficiency in neonate will lead to the development of dietary strategy aimed at enhancing L-arginine plasma concentrations.