Connor R I, Shen L, Fanger M W
Department of Microbiology, Dartmouth Medical School, Hanover, NH 03756.
J Immunol. 1990 Sep 1;145(5):1483-9.
In this report we present evidence that not all human peripheral blood monocytes mediate antibody-dependent cellular cytotoxicity (ADCC), and that this function may be determined on an individual cell by both the type and level of expression of FcR, and by the state of cellular activation and/or differentiation. Although the diverse range of effector and regulatory functions performed by human monocytes suggests the possibility of distinct subsets, it is not clear whether observed functional heterogeneity reflects the presence of true monocyte subpopulations, or whether this diversity represents a continuum of maturational states present in the peripheral circulation. In an attempt to address this question, we investigated the ability of human monocytes to carry out ADCC at the single cell level, with emphasis on the role of the three FcR for IgG (Fc gamma RI, Fc gamma RII, and Fc gamma RIII) in mediating cytotoxicity. Using a modified plaque assay, 58.3% +/- 4.9 of freshly isolated monocytes mediated ADCC, as evidenced by the formation of lytic plaques in monolayers of ox erythrocyte (oxE) target cells. Significant increases in the number of plaque-forming cells were observed after positive selection by flow microfluorimetry for those monocytes expressing high levels of Fc gamma RI and Rc gamma RII, but not Fc gamma RIII. Bispecific antibodies composed of Fab fragments of anti-oxE antibody covalently coupled to Fab fragments of anti-Fc gamma R antibodies were used to independently evaluate the ability of Fc gamma RI, Fc gamma RII, and Fc gamma RIII to mediate single cell cytotoxicity. Significant increases in the number of plaque-forming cells were observed in the presence of anti-Fc gamma RI x anti-oxE and anti-Fc gamma RII x anti-oxE bispecific antibodies, confirming the efficiency of Fc gamma RI and Fc gamma RII as cytotoxic trigger molecules on human monocytes. Incubation of monocytes with purified rIFN-gamma and granulocyte macrophage-CSF, but not IL-2, IL-3, IL-4, IL-6, or TNF-alpha, also resulted in significant increases in the number of monocytes mediating cytotoxicity, suggesting that cytotoxic ability at the single cell level may be influenced by factors which effect monocyte activation and differentiation, respectively. Overall, these studies demonstrate that freshly isolated human monocytes are heterogeneous in their ability to mediate ADCC, and suggest that this functional diversity arises not from discrete subpopulations of cells, but from a continuum of maturational/activational states present within the peripheral circulation.
在本报告中，我们提供的证据表明，并非所有人类外周血单核细胞都介导抗体依赖性细胞毒性（ADCC），并且该功能可能由FcR的表达类型和水平以及细胞活化和/或分化状态在单个细胞上决定。尽管人类单核细胞执行的多种效应和调节功能提示了存在不同亚群的可能性，但尚不清楚观察到的功能异质性是反映了真正的单核细胞亚群的存在，还是这种多样性代表了外周循环中存在的成熟状态的连续体。为了解决这个问题，我们在单细胞水平上研究了人类单核细胞进行ADCC的能力，重点关注三种IgG的FcR（FcγRI、FcγRII和FcγRIII）在介导细胞毒性中的作用。使用改良的蚀斑测定法，58.3%±4.9%的新鲜分离单核细胞介导了ADCC，牛红细胞（oxE）靶细胞单层中溶细胞蚀斑的形成证明了这一点。通过流式微荧光法对表达高水平FcγRI和FcγRII但不表达FcγRIII的单核细胞进行阳性选择后，观察到蚀斑形成细胞数量显著增加。由抗oxE抗体的Fab片段与抗FcγR抗体的Fab片段共价偶联组成的双特异性抗体被用于独立评估FcγRI、FcγRII和FcγRIII介导单细胞细胞毒性的能力。在存在抗FcγRI×抗oxE和抗FcγRII×抗oxE双特异性抗体的情况下，观察到蚀斑形成细胞数量显著增加，证实了FcγRI和FcγRII作为人类单核细胞上细胞毒性触发分子的效率。用纯化的rIFN-γ和粒细胞巨噬细胞集落刺激因子孵育单核细胞，但不用IL-2、IL-3、IL-4、IL-6或TNF-α，也导致介导细胞毒性的单核细胞数量显著增加，这表明单细胞水平的细胞毒性能力可能分别受影响单核细胞活化和分化的因素影响。总体而言，这些研究表明，新鲜分离的人类单核细胞在介导ADCC的能力上是异质的，并且表明这种功能多样性并非源于离散的细胞亚群，而是源于外周循环中存在的成熟/活化状态的连续体。
