Differentiation Of Mouse Bone Marrow Macrophage Precursor Cells Under The Influence Of Interleukin-2: Are Interleukin-2-activated Macrophage Precursor Cells Natural Killer (NK-) Cells

It is well known that NK-cells(natural killer cells)play an important role in the natural defense of immune system against neoplastic or virally infected cells,as well as certain microorganisms.Nevertheless,the cell lineage of NK-cells has not yet been clarified.In the present work the bone-marrow precursor cells,which could differentiate into NK-cells after activating with interleukin-2(NK-cytotoxicity stimulation),were studied under the bone-marrow culture conditions.It was found out that these NK-cell precursors from bone-marrow were dependent on myeloid growth factors: GM-CSF(granulocyte-macrophage colony stimulating factor)or CSF-1(colony stimulating factor 1,i.e.macrophage-colony stimulating factor),to proliferate.Incubating these NK-cell precursors only with CSF-1 or PMA(phorbol 12-myristate13-acetate),the factor which stimulates the cell-differentiation,the cells developed into typical mature macrophages in a short time(24-72 hours).Thus,these bone-marrow precursor cells,which were able to differentiate into NK-cells,were identified as macrophage precursors.Interleukin-2 is the crucial factor,which influences the differentiation of bone marrow macrophage precursors into the direction to NK-cells.Within 3-6 days of incubation with interleukin-2,these macrophage precursor cells developed first into NK-cells and then into LAK-cells(lymphokine-activated killer cells)which have been well known as the further activated form of NK-cells.The cell types were determined by morphological,phenotypic,and functional investigations.The experimental results presented in this work demonstrate that NK-/LAK-cells might derive from macrophage system.