Buhtoiarov Ilia N, Lum Hillary, Berke Gideon, Paulnock Donna M, Sondel Paul M, Rakhmilevich Alexander L
Department of Human Oncology and UW Comprehensive Cancer Center, University of Wisconsin, Madison, WI 53792, USA.
J Immunol. 2005 May 15;174(10):6013-22. doi: 10.4049/jimmunol.174.10.6013.
We have shown previously that agonistic anti-CD40 mAb induced T cell-independent antitumor effects in vivo. In this study, we investigated mechanisms of macrophage activation with anti-CD40 mAb treatment, assessed by the antitumor action of macrophages in vitro. Intraperitoneal injection of anti-CD40 mAb into C57BL/6 mice resulted in activation of peritoneal macrophages capable of suppressing B16 melanoma cell proliferation in vitro, an effect that was greatly enhanced by LPS and observed against several murine and human tumor cell lines. Anti-CD40 mAb also primed macrophages in vitro to mediate cytostatic effects in the presence of LPS. The tumoristatic effect of CD40 ligation-activated macrophages was associated with apoptosis and killing of tumor cells. Activation of macrophages by anti-CD40 mAb required endogenous IFN-gamma because priming of macrophages by anti-CD40 mAb was abrogated in the presence of anti-IFN-gamma mAb, as well as in IFN-gamma-knockout mice. Macrophages obtained either from C57BL/6 mice depleted of T and NK cells by Ab treatment, or from scid/beige mice, were still activated by anti-CD40 mAb to mediate cytostatic activity. These results argued against the role of NK and T cells as the sole source of exogenous IFN-gamma for macrophage activation and suggested that anti-CD40 mAb-activated macrophages could produce IFN-gamma. We confirmed this hypothesis by detecting intracytoplasmic IFN-gamma in macrophages activated with anti-CD40 mAb in vivo or in vitro. IFN-gamma production by macrophages was dependent on IL-12. Taken together, the results show that murine macrophages are activated directly by anti-CD40 mAb to secrete IFN-gamma and mediate tumor cell destruction.
我们之前已经表明，激动性抗CD40单克隆抗体在体内可诱导不依赖T细胞的抗肿瘤效应。在本研究中，我们通过体外巨噬细胞的抗肿瘤作用来研究抗CD40单克隆抗体治疗激活巨噬细胞的机制。向C57BL/6小鼠腹腔注射抗CD40单克隆抗体可导致腹腔巨噬细胞活化，这些活化的巨噬细胞能够在体外抑制B16黑色素瘤细胞增殖，脂多糖可大大增强这一效应，并且在几种小鼠和人类肿瘤细胞系中均观察到这一效应。抗CD40单克隆抗体还可在体外使巨噬细胞致敏，从而在脂多糖存在的情况下介导细胞生长抑制效应。CD40连接激活的巨噬细胞的肿瘤生长抑制效应与肿瘤细胞的凋亡和杀伤有关。抗CD40单克隆抗体激活巨噬细胞需要内源性干扰素-γ，因为在存在抗干扰素-γ单克隆抗体的情况下以及在干扰素-γ基因敲除小鼠中，抗CD40单克隆抗体对巨噬细胞的致敏作用均被消除。通过抗体处理使T细胞和NK细胞耗竭的C57BL/6小鼠或scid/beige小鼠获得的巨噬细胞，仍然可被抗CD40单克隆抗体激活以介导细胞生长抑制活性。这些结果反驳了NK细胞和T细胞作为巨噬细胞激活的外源性干扰素-γ唯一来源的作用，并表明抗CD40单克隆抗体激活的巨噬细胞可产生干扰素-γ。我们通过检测体内或体外被抗CD40单克隆抗体激活的巨噬细胞中的细胞质干扰素-γ证实了这一假设。巨噬细胞产生干扰素-γ依赖于白细胞介素-12。综上所述，结果表明小鼠巨噬细胞可被抗CD40单克隆抗体直接激活，从而分泌干扰素-γ并介导肿瘤细胞破坏。
