Arginine can be taken as a supplement and have quantifiable anti-tumor and anti-pathogen effects.

L-Arginine (L-Arg) plays a central role in the normal function of several organ systems including the immune system. Several reports have shown that the depletion of L-Arg. induces a profound decrease in T cell proliferation. We previously showed that culturing Jurkat T cells in media without L-Arginine (L-Arg) caused a rapid decrease in the expression in the CD3 z chain of the T cell receptor that parallels the decreased proliferation ( ). The aim of this study was to determine the mechanisms by which the depletion of L-Arg decreases the CD3 z chain. The data presented here shows that Jurkat cells cultured in L-Arg-free medium, had decrease after 24 hours on the expression of the T cell receptor z chain (CD3 z) (P<0.0001). This process was completely reversed after the replenishment of L-Arg into the tissue culture medium. Changes in the expression of CD3 z were not explained by an increase in apoptosis. Down-regulation of CD3 z protein induced by L-Arg starvation was associated with a decrease in the CD3 z mRNA levels. This drop in the CD3 z mRNA was mainly due to a diminished RNA stability. Furthermore, the effect of L-Arg starvation in the CD3 z mRNA stability was Actinomycin-D sensible. In conclusion, the concentration of L-Arg in the microenvironment plays a central role in regulating the expression of the CD3 z and as a consequence that of the T cell receptor.