Figure 1
From: Cystine and theanine: amino acids as oral immunomodulative nutrients
Working hypothesis regarding the immunomodulative actions of cystine and theanine. After the oral administration of cystine and theanine, cystine is incorporated into antigen-presenting cells (APCs: monocytes, Mϕ, or dendritic cells) which express cystine transporter (xCT/4F2hc) and reduced to cysteine. Theanine is hydrolyzed into glutamate and ethylamine and the glutamate is incorporated into APCs. The incorporated cysteine and glutamate enhance glutathione synthesis (Rimaniol et al. 2001) and then induce immunomodulative activity. On the other hand, the ethylamine derived from theanine acts on γδT cells (Bukowski et al. 1999).