IL-2 is produced mainly by conventional (CD4+CD25−FoxP3−) T helper cells (Th cells), whereas Treg cells do not express IL-2 and rely on IL-2-secreting Th cells

As far as I know, Treg do not produce IL-2, but is highly dependent of IL-2.

Treg cells don´t secrete IL-2

Thanks all!

sometimes do

Just for clarity's sake, I think Esaki Muthu Shankar meant IL2Ra (CD25, the unique component of the high-affinity IL-2 receptor).

Tregs (at least defined as stable Foxp3-expressing CD4+ T cells in mice) do not produce IL-2. Why Tregs require IL-2 is commonly confused, but the general reasons are well described. Tom Malek has written some helpful reviews on the subject. IL-2 improves both Treg survival and their suppressive function (http://www.ncbi.nlm.nih.gov/pubmed/21037099). And, although Tregs can be stimulated to proliferate with IL-2, they do not require IL-2 to divide in vivo.

Funny I got the same paper while googling on the same topic:-)

I think of the role of IL-2 as homeostatic in the maintenance of Tregs, in much the same way as IL-7 is involved in classical T cell homeostasis. In addition, the expression of the IL-2R by Tregs makes them susceptible to activation by the greater abundance of IL-2 at sites of established immune responses (probably at the level of individual DCs or aggregations of DCs), essential to their role in regulating or terminating on going responses.