Interleukin-11 (IL-11) acts as a synergistic factor for the proliferation of human myeloid leukaemic cells.
Interleukin-11 is a stromal cells derived cytokine which stimulates the proliferation of primitive haemopoietic progenitor cells. For this paper we have studied the constitutive expression of IL-11 mRNA in a panel of wellknown leukaemic cell lines and samples from AML patients at diagnosis. Moreover, the same cellular populations were evaluated for their proliferative response to recombinant-human-(r-hu). IL-11 alone and combined with r-hu-IL-3, granulocyte-macrophage colony stimulating factor (GM-CSF) and stem cell factor (SCF, c-kit ligand). The colony-forming ability of HL60, K562, KG1 cells and eight fresh AML cell populations was assessed by a clonogenic assay in methylcellulose. In eight additional AML cases the number of S-phase leukaemic cells induced by IL-11 was determined by the bromodeoxyuridine (BRDU) incorporation assay after 3d of liquid culture. IL-11, as single cytokine, did not stimulate the colony formation of the three myeloid cell lines under serum-containing and serum-free conditions. In contrast, the proliferation of the leukaemic cells in response to IL-3, GM-CSF and SCF was enhanced by co-incubation with IL-11, and this effect was reversed in blocking experiments by the anti-IL-11 Moab. When tested on primary AML samples, IL-11 alone showed little, if any, proliferative activity. However, it increased the IL-3-dependent blast colony formation in eight out of eight cases and GM-CSF in seven cases. IL-11 also augmented synergistically the number of CFU-L stimulated by SCF in seven cases. A combination of three factors (IL-11, SCF and IL-3) yielded optimal colony formation. The BRDU studies showed the significant increase of AML cells in S-phase when IL-11 was combined with SCF, whereas the two CSF had no activity on their own. Positive interaction was also observed when IL-11 was added to IL-3 supplemented cultures in five out of eight cases tested. Reverse transcriptase-polymerase chain reaction amplification (RT-PCR) demonstrated the constitutive expression of IL-11 mRNA in all the cell lines and 11/12 AML samples studied at diagnosis. These results indicate that IL-11 is expressed in leukaemic myeloid cells and that their proliferation is regulated by the cytokine which acts as a synergistic factor.
Lemoli
R M
RM
Institute of Haematology, University of Bologna, Italy.
Fogli
M
M
Fortuna
A
A
Amabile
M
M
Zucchini
P
P
Grande
A
A
Martinelli
G
G
Visani
G
G
Ferrari
S
S
Tura
S
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D002455:Cell Division / Q000502:physiology; D005260:Female; D006801:Humans; D017370:Interleukin-11 / Q000502:physiology*; D007951:Leukemia, Myeloid / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D016196:S Phase / Q000502:physiology; D014407:Tumor Cells, Cultured
D017370:Interleukin-11; D012333:RNA, Messenger