Lotem J, Sachs L
J Immunol. 1976 Aug;117(2):580-6.
An experimental system has been developed to study in cloned lines of cells the control of Fc and C3 receptors by different compounds. The cells used were clones of mouse myeloid leukemic cells and the compounds used were the protein MGI2 (macrophage and granulocyte inducer) in serum from mice injected with bacterial endotoxin and the steroid inducer (SI) dexamethasone. Eight clones were isolated which could be divided into three groups. One group (MGI+SI+) was induced to form EA and EAC rosettes by MGI and only EAC rosettes by SI, the second group (MGI-SI+) was not inducible by MGI but was induced by SI to form EA or EA and EAC rosettes, and the third group (MGI-SI-) was not inducible for EA or EAC by MGI or SI. There were two types of MGI+SI+ clones, one type (D+) could be induced by MGI to differentiate to mature macrophages and granulocytes, and the other type (D-) could not be induced to differentiate to mature cells. The MGI-SI+ and MGI-SI- clones were all D-. The results indicate that there are different cellular sites for MGI and SI and that induction of EA and EAC rosettes did not seem to be mediated by cyclic AMP. Experiments with specifically bound 3H-BSA-anti-BSA complexes have indicated that there was an increase in the amount of 3H-BSA-anti-BSA bound per rosette-forming cell following induction by MGI or SI, and there were differences in the amount of 3H-BSA-anti-BSA bound per rosette-forming cell in different clones. These clones also showed differences in the shape of the curve for the number of EA rosette-forming cells obtained with erythrocytes coated with decreasing concentrations of antibody. The results suggest that such curves and those obtained with EAC rosettes can be used to determine the relative abundance of EA and EAC receptors on rosette-forming cells. EA rosettes on the myeloid leukemic cells, like those on normal macrophages and granulocytes, were specifically inhibited by IgG2a and by the Fc but not the Fab fragment of IgG. The EAC rosettes were inhibited by destroying the C3 component of complement. The different clones maintained their specific properties for at least 6 months in culture. The present system should, therefore, also be useful for studies on the genetic control of the regulation of Fc and C3 receptors.
已开发出一种实验系统，用于在细胞克隆系中研究不同化合物对Fc和C3受体的控制。所用细胞为小鼠髓样白血病细胞克隆，所用化合物为注射细菌内毒素的小鼠血清中的蛋白质MGI2（巨噬细胞和粒细胞诱导剂）和类固醇诱导剂（SI）地塞米松。分离出八个克隆，可分为三组。一组（MGI+SI+）被MGI诱导形成EA和EAC玫瑰花结，被SI诱导仅形成EAC玫瑰花结；第二组（MGI-SI+）不能被MGI诱导，但被SI诱导形成EA或EA和EAC玫瑰花结；第三组（MGI-SI-）不能被MGI或SI诱导形成EA或EAC。有两种类型的MGI+SI+克隆，一种类型（D+）可被MGI诱导分化为成熟巨噬细胞和粒细胞，另一种类型（D-）不能被诱导分化为成熟细胞。MGI-SI+和MGI-SI-克隆均为D-。结果表明，MGI和SI存在不同的细胞作用位点，且EA和EAC玫瑰花结的诱导似乎不是由环磷酸腺苷介导的。用特异性结合的3H-BSA-抗BSA复合物进行的实验表明，在MGI或SI诱导后，每个形成玫瑰花结的细胞上结合的3H-BSA-抗BSA量增加，且不同克隆中每个形成玫瑰花结的细胞上结合的3H-BSA-抗BSA量存在差异。这些克隆在用浓度逐渐降低的抗体包被的红细胞获得的EA玫瑰花结形成细胞数量的曲线形状上也存在差异。结果表明，这样的曲线以及用EAC玫瑰花结获得的曲线可用于确定形成玫瑰花结的细胞上EA和EAC受体的相对丰度。髓样白血病细胞上的EA玫瑰花结，与正常巨噬细胞和粒细胞上的一样，被IgG2a以及IgG的Fc片段而非Fab片段特异性抑制。EAC玫瑰花结通过破坏补体的C3成分而被抑制。不同克隆在培养中至少6个月保持其特异性特性。因此，本系统也应有助于研究Fc和C3受体调节的遗传控制。
