Transiently increased circulating CD39+FoxP3+ Treg cells predict the clinical response to Methotrexate in Early Rheumatoid Arthritis

A subset of human circulating FoxP3+ regulatory T cells expresses CD39 (cTreg39+) and hydrolyses pro-inflammatory adenine nucleotides released at inflammatory foci, rendering the anti-inflammatory agent adenosine. Methotrexate (MTX), inhibiting ATIC, enhances the extrusion of adenine nucleotides and may help Treg39+ cells control inflammation. Therefore, we examined the relation of cTreg39+ cells with the effect of MTX in early Rheumatoid Arthritis (eRA).