Purpose: Acute myeloblastic leukaemia (AML) cells respond to some extent to the action of haemopoietic growth factors (HGF). This work is aimed to analyse the effect of IL-3, GM-CSF and G-CSF on the proliferative and self-replication capabilities of AML cells and to correlate such response with the morphological and immunological characteristics of the blast cells.
Patients and methods: Mononucleated cells from the peripheral blood of 26 AML patients were incubated in liquid medium without serum in presence of IL-3 and GM-CSF alone and in combination with G-CSF. Cell proliferation was evaluated by determination of the increase in the number of cells harvested after incubation with the HGF. The proliferative response was studied in 8 cases by flow cytometry analysis of the cell cycle (number of cells in S-phase). The capability of IL-3 and GM-CSF to induce self-replication of the leukaemic clonogenic cell (CFU-L) was analysed in 9 cases by techniques of replanting on semi-solid medium.
Results: Cell proliferation was induced with IL-3 in more cases than with GM-CSF (50% vs 28%); furthermore, the stimulus induced by IL-3 was also more evident, as the number of cells harvested was greater than that corresponding to GM-CSF (2.1 +/- 1.1 x 10(6) cell/mL vs 1.4 +/- 1.4 x 10(6) cells/mL, p = 0.10). Although no clear correlation was seen between the proliferative response to HGF and the immunologic or morphologic subtype of the blast cells, no response to GM-CSF was detected in those cases classified as M2 nor in the CD15-positive leukaemias. A synergistic effect of G-CSF and IL-3 or GM-CSF was found in only 20% of the cases. Both IL-3 and GM-CSF augmented the number of cells in S phase in all the cases analysed; this increase was higher in M1 and M2 with respect to the leukaemias with monocytic component.
Conclusions: IL-3 and GM-CSF induced self-replication of CFU-L in a half of the cases. This effect was not dependent upon the kind of stimulating agent used (IL-3 or GM-CSF), and appeared unrelated to the morphologic or immunologic characteristics of the leukaemia.