Systemic administration of 5-aza-C has been reported to ameliorate clinical symptoms in murine models of undesired immunity [ovalbumin-induced airway hyperresponsiveness (58) and virus-induced ocular infection (45)], perhaps by promoting the accumulation of Foxp3+ Treg cells with increased expression of Treg cell signature proteins (CD25, FR4, and GITR) and suppressor function (45). Here, TNFRSF18 is linked to airway hyperresponsiveness.