| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1987: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1986: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
Natural killer (NK) cells, morphologically indistinguishable from large granular lymphocytes (LGLs), are thought to have an important role in the regulation of hematopoiesis. A clonal leukemic population of NK cells was isolated from a 14-year-old girl. They had a Leu-11^+, Leu-7^- phenotype. Since the NK activity was low but was remarkably augmented by stimulation with recombinant human interleukin 2 (rIL-2), but not interferon- (IFN-<gamma>), this NK subset seems to belong to a premature stage in the maturation of NK cells. Because of severe neutropenia throughout the clinical course, we investigated the effects of this NK subpopulation on the in vitro growth of granulocyte-macrophage colony forming cells (GM-CDC). When this NK subset in the presence of rIL-2 was added to the GM-CFC assay system employing normal bone marrow cells, a remarkable suppression of GM-CFC was demonstrated. Culture supernatants from the rIL-2-stimulated NK cells, which had a high level of IFN-<gamma>, also exhibited a significant suppressive activity. Treatment of the supernatants with a specific antibody against IFN-<gamma> abrogated the inhibitory effect on GM-CFC. These data indicate that this unique subset of premature NK cells in the presence of rIL-2 produceIFN-<gamma> which seems to be involved in the suppression of myelopoietic progenitor cells.
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