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Effect of recombinant interferons alpha and gamma on human bone marrow-derived megakaryocytic progenitor cells
A Ganser1, C Carlo-Stella, J Greher
1Department of Hematology, University of Frankfurt, FR Germany.
Abstract:
Interferons (IFNs) have been shown to suppress the proliferation of human pluripotent hematopoietic progenitor cells, CFU-GEMM, and committed erythroid (BFU-E, CFU-E) and granulocyte-macrophage (CFU-GM) progenitor cells. However, no information is yet available concerning the effect of IFNs on human megakaryocytic progenitor cells CFU-Mk. Furthermore the mechanisms underlying the inhibitory activity of IFNs are still controversial. Therefore highly purified recombinant IFN preparations, rIFN-alpha and rIFN-gamma, were assessed for their influence on in vitro growth of human bone marrow-derived CFU-Mk as well as CFU-GEMM. In addition, the role of hematopoietic accessory cells, that is, adherent cells and T lymphocytes, in the mediation of the suppressive effect of rIFNs was examined. When added to unseparated bone marrow cells, both rIFN preparations significantly inhibited colony formation with 50% inhibition of CFU-Mk occurring at 22 U/mL for rIFN-alpha and 59 U/mL for rIFN-gamma, while 50% inhibition of CFU-GEMM occurred at 59 U/mL for rIFN-alpha and 101 U/mL for rIFN-gamma. The suppressive effect of rIFN-alpha and rIFN-gamma was selectively abolished by monoclonal antibodies (MoAbs) against rIFN-alpha and rIFN-gamma, thus confirming that the inhibitory activity was due to the rIFN preparations used. The antiproliferative effect of rIFN-alpha and rIFN-gamma on CFU-GEMM growth was not associated with a decrease in the percentage of mixed colonies containing megakaryocytic cells as assessed by use of the MoAb C17.28 against platelet glycoprotein IIIa. Removal of adherent cells and T lymphocytes from the target bone marrow cells had no influence on the suppressive effect of rIFN-alpha, whereas it significantly reduced the inhibitory effect of rIFN-gamma on the growth of megakaryocytic colonies and the other hematopoietic progenitors. The data indicate that (1) human megakaryocytopoiesis is markedly inhibited by rIFN-alpha and rIFN-gamma, and (2) the inhibitory effect of rIFN-alpha is due to a direct action on hematopoietic progenitor cells, whereas the effect of rIFN-gamma is mediated to a significant degree through accessory cell populations.
Insights
Interferons (IFNs) suppress human megakaryocytopoiesis. Recombinant IFN-alpha acts directly on progenitors, while IFN-gamma
Area of Science:
- Hematology
- Immunology
- Cell Biology
Background:
- Interferons (IFNs) are known to inhibit hematopoietic progenitor cell proliferation.
- The specific effects of IFNs on human megakaryocytic progenitor cells (CFU-Mk) and the mechanisms of inhibition remain unclear.
Purpose of the Study:
- To investigate the in vitro effects of recombinant interferon-alpha (rIFN-alpha) and recombinant interferon-gamma (rIFN-gamma) on human megakaryocytopoiesis.
- To elucidate the role of accessory hematopoietic cells in mediating the suppressive effects of rIFNs.
Main Methods:
- Assessing the influence of rIFN-alpha and rIFN-gamma on in vitro growth of human bone marrow-derived CFU-Mk and CFU-GEMM.
- Examining the role of adherent cells and T lymphocytes in rIFN-mediated suppression using monoclonal antibodies.
Main Results:
- Both rIFN-alpha and rIFN-gamma significantly inhibited CFU-Mk and CFU-GEMM colony formation.
- rIFN-alpha's suppressive effect was direct on progenitor cells, unaffected by accessory cell removal.
- rIFN-gamma's inhibitory effect was significantly reduced upon removal of accessory cells, indicating indirect action.
Conclusions:
- Human megakaryocytopoiesis is markedly inhibited by both rIFN-alpha and rIFN-gamma.
- rIFN-alpha exerts its inhibitory effect directly on hematopoietic progenitor cells.
- rIFN-gamma's suppressive action is largely mediated through accessory hematopoietic cell populations.