L-arginine regulates the expression of the T-cell receptor zeta chain (CD3zeta) in Jurkat cells

L-Arginine is a versatile amino acid that plays a central role in the norma l function of several organ systems including the immune system. Its availa bility is tightly controlled and varies significantly in different organs a nd tissues in the body. L-Arginine plays an important role in supporting T- cell proliferation, Its depletion in certain disease states results in a di minished T-cell response. The main purpose of this study was to determine t he effect of the depletion of L-arginine on the expression of the T-cell re ceptor (TCR) proteins. When the helper T-cell line Jurkat was cultured in a rginine-free medium, there was a preferential decrease in the expression of the TCR zeta chain (CD3 zeta), The reduced expression of CD3 zeta was obse rved within 24 h of culture in L-arginine-free medium and was completely re versed,vith the replenishment of L-arginine, Furthermore, the absence of L- arginine blocked the normal re-expression of the TCR that had been internal ized after antigen stimulation, There also was a significant decrease in pr oliferation of Jurkat cells in the absence of L-arginine; however, L-argini ne depletion dib not prevent the up-regulation of the interleukin 2 recepto r chains upon stimulation, nor did it significantly diminish the production of interleukin 2, The changes in the expression of CD3 zeta chain were not induced by apoptosis, Thus, the availability of L-arginine in the microenv ironment may play a significant role in regulating the expression of the TC R.