ADA and rheumatoid arthritis: The anti-inflammatory effect of low-dose MTX used to treat JIA and RA is thought to be due the anti-inflammatory effects of adenosine, formed as a consequence of the inhibitory effects of MTX on amino-imidazole carboxamide ribonucleotide (AICAR) transformylase (gene name, ATIC), which promotes the accumulation of AICAR ribotide, inhibiting adenosine deaminase and leading to a build up of adenosine, a potent anti-inflammatory agent[30].