NT5E (CD73) is a surface enzyme which is expressed on multiple cells. This enzyme mediates the gradual hydrolysis of the autocrine and paracrine danger signals of ATP and ADP to anti-inflammatory adenosine. Immune suppression mediated by adenosinergic pathways is very important for maintaining immune system homeostasis. Immune suppressive functions of T regulatory cells are also dependent on CD73 expression. CD73 also occurs on anergic CD4 + T cells, thereby maintaining self-tolerance to healthy tissues as well as protecting the fetus from the mother's immune system during pregnancy.