Fais S, Burgio V L, Silvestri M, Capobianchi M R, Pacchiarotti A, Pallone F
Istituti di Clinica Medica 2, Virologia, di Anatomia Patologica 2 Universita' La Sapienza, Roma, Italy.
Lab Invest. 1994 Nov;71(5):737-44.
Multinucleated giant cells (MGC), interferon-gamma (IFN-gamma) production, and increased expression of adhesion molecules are features of granulomatous reactions. IFN-gamma induces the fusion of macrophages and the subsequent MGC generation in vitro. Moreover, IFN-gamma increases ICAM-1 expression on lymphoid cells and an important role for adhesion molecules in MGC generation has been proposed.
The time course of the IFN-gamma-driven MGC generation was investigated in slide-chamber cultures of adherence-purified human monocytes. The fusion index, the monocytes clustering the total number of MGC were determined. The expression of intercellular cell adhesion molecule-1 (ICAM-1), LFA-1 and HLA-DR was investigated by immunohistochemistry. The effect of anti-ICAM-1, anti-LFA-1 and anti-HLA-DR monoclonal antibodies on IFN-gamma-induced MGC generation was also examined.
IFN-gamma enhanced the generation of MGC in a dose- and time-dependent fashion. In all experiments, MGC formation was preceded by a sequence of changes in the morphology of cultured monocytes. Cell clustering occurred as early as 3 days after IFN-gamma stimulation and was followed by the adhesion of cells that eventually fused. Immunohistochemistry showed that ICAM-1 was increased by IFN-gamma and constantly polarized on a cell uropode. When monocytes clustered, ICAM-1 was localized on the membrane where the cell-to-cell contact occurred. In newly formed MGC, ICAM-1 stained in the center of the giant cell. The cellular distribution of LFA-1 on cultured monocytes was not modified by IFN-gamma. HLA-DR expectedly enhanced by IFN-gamma was mostly cytoplasmic and tended to disappear when MGC formed. Finally, anti-LFA-1 and anti-ICAM-1 monoclonal antibodies variably inhibited IFN-gamma-induced MGC generation.
Taken together, these data add support to the concept that IFN-gamma is essential for MGC generation by promoting cell clustering and cell-to-cell adhesion. The present data also indicate that among the mechanisms by which IFN-gamma exert such a promoting effect, changes in the ICAM-1 expression and cellular distribution are included. The observation that ICAM-1 appears to be trapped in the cytoplasm of IFN-gamma-driven MGC and that HLA-DR tend to disappear from macrophages undergoing MGC formation, also suggest changes in the functional properties of these cells.
多核巨细胞（MGC）、γ干扰素（IFN-γ）的产生以及黏附分子表达增加是肉芽肿反应的特征。IFN-γ在体外可诱导巨噬细胞融合并随后生成MGC。此外，IFN-γ可增加淋巴细胞上细胞间黏附分子-1（ICAM-1）的表达，并且有人提出黏附分子在MGC生成中起重要作用。
在贴壁纯化的人单核细胞的玻片培养室培养物中研究了IFN-γ驱动的MGC生成的时间进程。测定了融合指数，即聚集形成MGC总数的单核细胞数量。通过免疫组织化学研究细胞间黏附分子-1（ICAM-1）、淋巴细胞功能相关抗原-1（LFA-1）和人类白细胞抗原DR（HLA-DR）的表达。还检测了抗ICAM-1、抗LFA-1和抗HLA-DR单克隆抗体对IFN-γ诱导的MGC生成的影响。
IFN-γ以剂量和时间依赖性方式增强MGC的生成。在所有实验中，MGC形成之前培养的单核细胞形态会发生一系列变化。早在IFN-γ刺激后3天就出现细胞聚集，随后是最终融合的细胞黏附。免疫组织化学显示，IFN-γ可增加ICAM-1的表达，并在细胞尾足持续极化。当单核细胞聚集时，ICAM-1定位于细胞间接触发生的膜上。在新形成的MGC中，ICAM-1在巨细胞中心染色。IFN-γ未改变培养的单核细胞上LFA-1的细胞分布。IFN-γ预期增加的HLA-DR大多位于细胞质中，当MGC形成时趋于消失。最后，抗LFA-1和抗ICAM-1单克隆抗体可不同程度地抑制IFN-γ诱导的MGC生成。
综上所述，这些数据支持了IFN-γ通过促进细胞聚集和细胞间黏附对MGC生成至关重要的概念。目前的数据还表明，在IFN-γ发挥这种促进作用的机制中，包括ICAM-1表达和细胞分布的变化。ICAM-1似乎被困在IFN-γ驱动的MGC细胞质中以及HLA-DR在经历MGC形成的巨噬细胞中趋于消失的观察结果，也提示了这些细胞功能特性的变化。
