Interleukin-1 alpha as an autocrine growth factor for acute lymphoblastic leukaemia cells.

We describe a case of B-lineage acute lymphoblastic leukaemia (ALL) with proliferation of leukaemic cells through an interleukin-1 alpha (IL-1 alpha) autocrine mechanism. Flow cytometric analysis using the IL-1 receptor type II (IL-1Rt II) monoclonal antibody (mAb) demonstrated the expression of the IL-1Rt II on leukaemic cells: this is the first report in IL-1RtII-positive freshly isolated ALL cells from a patient. In accordance with the expression of IL-1RtII, the leukaemic cells proliferated in response to exogenous IL-1 alpha. In addition, anti-IL-1 alpha mAb markedly inhibited the spontaneous cell proliferation. Furthermore, Northern blot analysis detected IL-1 alpha mRNA without any stimulation. These observations suggest that IL-1 alpha may play an important role as an autocrine growth factor in some cases of ALL.