Celada A, Gray P W, Rinderknecht E, Schreiber R D
J Exp Med. 1984 Jul 1;160(1):55-74. doi: 10.1084/jem.160.1.55.
Gamma-interferon (IFN-gamma) is the macrophage-activating factor (MAF) produced by normal murine splenic cells and the murine T cell hybridoma 24/G1 that induces nonspecific tumoricidal activity in macrophages. Incubation of 24/G1 supernatants diluted to 8.3 IRU IFN-gamma/ml with 6 X 10(6) elicited peritoneal macrophages or bone marrow-derived macrophages for 4 h at 37 degrees C, resulted in removal of 80% of the MAF activity from the lymphokine preparation. Loss of activity appeared to result from absorption and not consumption because (a) 40% of the activity was removed after exposure to macrophage for 30 min at 4 degrees C, (b) no reduction of MAF activity was detected when the 24/G1 supernatant was incubated with macrophage culture supernatants, and (c) macrophage-treated supernatants showed a selective loss of MAF activity but not interleukin 2 (IL-2) activity. Absorption was dependent on the input of either IFN-gamma or macrophages and was time dependent at 37 degrees C but not at 4 degrees C. With four rodent species tested, absorption of murine IFN-gamma displayed species specificity. However, cultured human peripheral blood monocytes and the human histiocytic lymphoma cell line U937 were able to absorb the murine lymphokine. Although the majority of murine cell lines tested absorbed 24/G1 MAF activity, two murine macrophage cell lines, P388D1 and J774, were identified which absorbed significantly reduced amounts of natural IFN-gamma. Purified murine recombinant IFN-gamma was absorbed by elicited macrophages but not by P388D1. Normal macrophages but not P388D1 bound fluoresceinated microspheres coated with recombinant IFN-gamma and binding was inhibited by pretreatment of the normal cells with 24/G1 supernatants. Scatchard plot analysis showed that 12,000 molecules of soluble 125I-recombinant IFN-gamma bound per bone marrow macrophage with a Ka of 0.9 X 10(8) M-1. Binding was quantitatively inhibitable by natural IFN-gamma but not by murine IFN alpha. IFN-beta competed only weakly. Monoclonal antibodies against IFN-gamma either inhibited or enhanced MAF activity by blocking or increasing IFN-gamma binding to macrophages, respectively. These results indicate that IFN-gamma reacts with a receptor on macrophage in a specific and saturable manner and this interaction initiates macrophage activation.
γ-干扰素（IFN-γ）是由正常小鼠脾细胞和小鼠T细胞杂交瘤24/G1产生的巨噬细胞激活因子（MAF），可诱导巨噬细胞产生非特异性杀肿瘤活性。将稀释至8.3国际参考单位（IRU）IFN-γ/毫升的24/G1上清液与6×10⁶个诱导的腹腔巨噬细胞或骨髓来源的巨噬细胞在37℃孵育4小时，导致淋巴因子制剂中80%的MAF活性丧失。活性丧失似乎是由于吸附而非消耗，因为：（a）在4℃与巨噬细胞接触30分钟后，40%的活性被去除；（b）当24/G1上清液与巨噬细胞培养上清液孵育时，未检测到MAF活性降低；（c）经巨噬细胞处理的上清液显示MAF活性选择性丧失，但白细胞介素2（IL-2）活性未丧失。吸附取决于IFN-γ或巨噬细胞的输入量，且在37℃时具有时间依赖性，在4℃时则无。在测试的四种啮齿动物物种中，小鼠IFN-γ的吸附表现出物种特异性。然而，培养的人外周血单核细胞和人组织细胞淋巴瘤细胞系U937能够吸附小鼠淋巴因子。尽管测试的大多数小鼠细胞系都能吸附24/G1 MAF活性，但鉴定出两种小鼠巨噬细胞系P388D1和J774，它们吸附的天然IFN-γ量显著减少。纯化的小鼠重组IFN-γ可被诱导的巨噬细胞吸附，但不能被P388D1吸附。正常巨噬细胞而非P388D1能结合包被有重组IFN-γ的荧光微球，且用24/G1上清液预处理正常细胞可抑制结合。Scatchard图分析显示，每个骨髓巨噬细胞结合12,000个可溶性¹²⁵I-重组IFN-γ分子，解离常数（Ka）为0.9×10⁸ M⁻¹。天然IFN-γ可定量抑制结合，而小鼠IFN-α则不能。IFN-β的竞争作用较弱。抗IFN-γ单克隆抗体分别通过阻断或增加IFN-γ与巨噬细胞的结合来抑制或增强MAF活性。这些结果表明，IFN-γ以特异性和可饱和的方式与巨噬细胞上的受体反应，这种相互作用启动巨噬细胞激活。
