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JP Hu, A Cesano, D Santoli, SC Clark and T Hoang
Clinical Research Institute of Montreal, Quebec, Canada.
Interleukin-11 (IL-11) is a pleiotropic cytokine with effects on many
different targets. Within the hematopoietic system, the effects of IL- 11
are largely manifest only through combination with other cytokines,
including IL-3 and Steel factor (SF). In the present study, we addressed
the question of IL-11 responsiveness within the different types of human
leukemic cells, as well as the mechanism of action of IL- 11 at the
cellular level. Analysis of a panel of samples from different patients with
acute myeloblastic leukemia (AML) and myeloid leukemic cell lines indicated
that IL-11 alone was ineffective in supporting myeloid leukemic cell growth
but frequently enhanced growth supported by IL-3, granulocyte-macrophage
colony-stimulating factor (GM-CSF), or SF. In contrast, three acute pre-B
lymphocytic leukemia (pre-B-ALL) and two acute T lymphocytic leukemia
(T-ALL) lines failed to respond to IL- 11 alone or when combined with other
cytokines. The growth enhancement of IL-11 among the AML patient samples
was dose dependent and remarkably constant with half-efficient
concentrations in the range of 0.3 to 0.4 ng/mL. The thymidine suicide
studies with the patient samples revealed that 40% to 50% of the blast
cells were in S-phase when exposed for 16 hours to IL-3 and this level was
increased to 70% to 90% in response to either IL-11 or IL-6. Our data
suggest that the latter two interleukins act synergistically with the
direct mitogenic factor, IL-3, in triggering AML blast-cell proliferation.
Detailed analysis with several patient samples further revealed that SF and
IL- 11 both enhance IL-3-supported clonogenic growth of AML blasts and the
combination of all three growth factors yields optimal growth. In contrast,
IL-6 does not further enhance the effect of IL-11. These results indicate
that SF and IL-11 enhance IL-3-dependent clonogenic growth through two
distinct pathways, whereas IL-6 and IL-11 may trigger the same pathway.
This article has been cited by other articles:
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| Copyright © 1993 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||