Yoshida R, Murray H W, Nathan C F
Beatrice and Samuel A. Seaver Laboratory, Department of Medicine, Cornell University Medical College, New York, New York 10021.
J Exp Med. 1988 Mar 1;167(3):1171-85. doi: 10.1084/jem.167.3.1171.
H2O2-releasing capacity and limited antitoxoplasma activity could be induced in human macrophages (derived from monocytes cultured greater than or equal to 5 d) but not in monocytes themselves (cells cultured less than or equal to 4 d) by a further 3-d incubation with pure natural or rIFN-alpha or -beta. More than 3 pM (10 U/ml) of these IFNs was required, with greatest effects at approximately 300 pM (10(3) U/ml). At 300 pM, H2O2-releasing capacity was enhanced 4.4 +/- 1.6-fold over medium control (mean +/- SD for natural INF-alpha, rIFN-alpha A, rIFN-alpha D, and rIFN-beta) compared to an 8.4 +/- 4.8-fold increase with rIFN-gamma (100 pM, 100 U/ml) in the same experiments. Unexpectedly, low concentrations of IFN-alpha or -beta (3 fM-300 pM) blocked induction of H2O2-releasing capacity by rIFN-gamma (10 pM), with a 50% inhibitory dose of approximately 80 fM. However, IFN-alpha or -beta (3 fM-300 pM) could not inhibit the effect of higher concentrations of rIFN-gamma (1 nM). In contrast to results with monocytes or young macrophages, Scatchard plots of binding of 125I-rIFN-gamma to mature macrophages (day 8 of culture) indicated two classes of binding sites: approximately 2,000 high-affinity sites (Kd approximately 0.43 nM) and approximately 23,000 low-affinity sites (Kd approximately 6.4 nM) per cell. Binding of 125I-rIFN-gamma to the high- but not the low-affinity sites was blocked by simultaneously added IFN-alpha or -beta, with a 50% inhibitory dose of approximately 2 U/0.25 ml (approximately 2 pM), or reversed by subsequently added IFN-alpha or -beta. Thus, differentiation of human mononuclear phagocytes in vitro is accompanied by the emergence of (a) an agonist response to submicromolar concentrations of IFN-alpha or -beta, (b) antagonism of the effect of picomolar IFN-gamma by femtomolar IFN-alpha or -beta, (c) two classes of IFN-gamma-Rs, and (d) nonstimulatory binding of IFN-alpha or -beta to the high- but not the low-affinity IFN-gamma-Rs, with higher affinity than rIFN-gamma itself. We speculate that traces of IFN-alpha or -beta derived from stromal cells, parenchymal cells, or resident macrophages may dampen the activation of mature tissue macrophages by the small amounts of IFN-gamma that diffuse from inflammatory sites into normal tissues. Such a mechanism could constrain the potentially destructive phenomenon of macrophage activation to areas where monocytes have recently immigrated and/or the concentration of IFNs is high.
通过与纯天然干扰素或重组人干扰素α或β再孵育3天，人巨噬细胞（源自培养≥5天的单核细胞）可被诱导产生H2O2释放能力及有限的抗弓形虫活性，但单核细胞本身（培养≤4天的细胞）则不能。这些干扰素的浓度需超过3 pM（10 U/ml），在约300 pM（10³ U/ml）时效果最佳。在300 pM时，与培养基对照相比，H2O2释放能力增强了4.4±1.6倍（天然干扰素α、重组人干扰素α A、重组人干扰素α D和重组人干扰素β的平均值±标准差），而在相同实验中，重组人干扰素γ（100 pM，100 U/ml）可使其增加8.4±4.8倍。出乎意料的是，低浓度的干扰素α或β（3 fM - 300 pM）可阻断重组人干扰素γ（10 pM）诱导的H2O2释放能力，半数抑制剂量约为80 fM。然而，干扰素α或β（3 fM - 300 pM）不能抑制高浓度重组人干扰素γ（1 nM）的作用。与单核细胞或年轻巨噬细胞的结果不同，125I - 重组人干扰素γ与成熟巨噬细胞（培养第8天）结合的Scatchard图显示有两类结合位点：每个细胞约有2000个高亲和力位点（解离常数Kd约为0.43 nM）和约23000个低亲和力位点（Kd约为6.4 nM）。同时加入的干扰素α或β可阻断125I - 重组人干扰素γ与高亲和力而非低亲和力位点的结合，半数抑制剂量约为2 U/0.25 ml（约2 pM），或者随后加入的干扰素α或β可使其解离。因此，人单核吞噬细胞在体外分化过程中伴随着以下现象的出现：（a）对亚微摩尔浓度的干扰素α或β产生激动剂反应；（b）飞摩尔浓度的干扰素α或β对皮摩尔浓度的干扰素γ的作用产生拮抗；（c）两类干扰素γ受体；（d）干扰素α或β与高亲和力而非低亲和力的干扰素γ受体结合但不产生刺激作用，且亲和力高于重组人干扰素γ本身。我们推测，来自基质细胞、实质细胞或驻留巨噬细胞的微量干扰素α或β可能会抑制从炎症部位扩散到正常组织的少量干扰素γ对成熟组织巨噬细胞的激活。这样一种机制可能会将巨噬细胞激活这一潜在的破坏现象限制在单核细胞最近迁入的区域和/或干扰素浓度较高的区域。
