IL-2/IL-3 interplay mediates growth of CD25 positive acute myeloid leukemia cells.

Cell surface interleukin-2 receptor α-chain (IL-2Rα, CD25) expression is currently recognized to be a strong predictor for poor prognosis in patients with acute myeloid leukemia (AML). However, it is still unknown that the reason why CD25 positive AML patients have a dismal clinical outcome. CD25 positive AML cells are generally unresponsive to IL-2, but strongly respond to IL-3. The levels of IL-3Rα on these AML cells are very high and directly proportional to the CD25 levels. T-lymphocytes produce IL-3 in response to stimuli including IL-2-mediated activation. Thus, CD25 on AML cells may capture environmental IL-2 and deliver it to the surrounding T-lymphocytes expressing IL-2Rβ/γc, leading to the production of IL-3 as a growth stimulus to CD25 positive AML cells. We hypothesize that IL-2/IL-3 interplay via CD25 is responsible for the growth property of CD25 positive AML, which may affect clinical behavior of those patients.