IL10 and allergic asthma: Suppression by Tregs in the allergic asthma model is likely mediated by IL-10 released by activated Tregs in high levels (13); other mechanisms may likewise apply such as induced cell death of responder T cells (36) and inhibition of T cell proliferation by upregulating cyclic adenosine monophosphate (37) or by CD39- and CD73-dependent peri-cellular generation of adenosine (38).