| Abstrakt: |
Culturing human monocytes in the presence of granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) and interleukin‐4 (IL‐4) has been reported to provoke the formation of multinucleated giant cells (GCs). In the present work, GCs were generated in a two‐step procedure in which macrophages were first differentiated from monocytes before being fused into GCs. The two cytokines used acted sequentially. GM‐CSF was required for monocyte differentiation and IL‐4 for macrophage fusion. Macrophages were purified from cultures of blood mononuclear cells maintained for 7 days in plastic bags. When seeded in conventional plastic‐ware in the presence of IL‐4, these macrophages showed an increased motility, spread in thin cytoplasmic lamellae, regrouped in clusters, and within 1–3 weeks, differentiated into GCs. Multinucleated cells also appeared in IL‐4‐untreated macrophage cultures but the number of nuclei did not exceed 2 or 3, compared with more than 30 in the presence of IL‐4. Scanning electron microscopy of GCs showed highly developed pseudopods. GCs reacted with anti‐CD11b, ‐CD54, ‐CD68, ‐HLA‐ABC, and ‐HLA‐DR monoclonal antibodies and AMH‐152 but were CD14‐ and CD64‐negative. Both untreated and IL‐4‐treated macrophages conserved pinocytic and phagocytic activity. Thus, IL‐4 induced a differentiation process in which macrophages lost markers like CD14 and CD64, acquired an enhanced membrane motility, and fused in multinucleated GCs. J. Leukoc. Biol. 61: 517–521; 1997. |
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