Weetall M, Holowka D, Baird B
Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, NY 14853-1301.
J Immunol. 1993 May 1;150(9):4072-83.
To study the properties of Fc epsilon RI desensitization induced by aggregation of that receptor, RBL cells were sensitized with a mixture of two different IgE mAb to create two different populations of IgE-receptor complexes. Cross-linking of one receptor population containing anti-dinitrophenyl (DNP) IgE with a bivalent Ag, 1-DNP-amino-12-biotinamidododecane)2-avidin ((DNP)2-avidin), results in desensitization of a subsequent response, both of the same receptor population (homologous desensitization) and of the second receptor population containing anti-5-dimethylaminonaphthalene-1-sulfonyl (dansyl) IgE (heterologous desensitization). The extent of heterologous desensitization is dependent on several parameters, including the concentration of both the first and the second Ag and the densities of the respective IgE populations. Heterologous desensitization of the Ca2+ response is more sensitive to the concentration of the second stimulus (dansyl-BSA) than heterologous desensitization of the degranulation response. AlF4-, which activates GTP-binding proteins, can effectively replace (DNP)2-avidin as the initial stimulant and desensitizing agent. Other agents that mobilize intracellular Ca2+ including thrombin and a Ca2+ ionophore are less effective at replacing (DNP)2-avidin. Because prestimulation with Ag does not desensitize subsequent responses to AlF4- or Ca2+ ionophore, it appears that signal transduction via Fc epsilon RI is impaired at an early step. Addition of monovalent DNP hapten within approximately 10 min after cross-linking by (DNP)2-avidin completely prevents the desensitization of the subsequent Ca2+ or degranulation response to dansyl-BSA. After longer times of incubation with DNP Ag, the DNP hapten becomes increasingly less effective at preventing the desensitization of the dansyl-BSA response, even though ongoing signal transduction by the DNP Ag is halted. These results suggest a form of cellular memory for the desensitized state.
为研究由FcεRI受体聚集诱导的脱敏特性，用两种不同的IgE单克隆抗体混合物使RBL细胞致敏，以产生两种不同群体的IgE - 受体复合物。用二价抗原1 - 二硝基苯基 - 氨基 - 12 - 生物素酰胺十二烷）2 - 抗生物素蛋白（（DNP）2 - 抗生物素蛋白）交联含抗二硝基苯基（DNP）IgE的一个受体群体，会导致后续反应脱敏，包括同一受体群体的反应（同源脱敏）以及含抗5 - 二甲基氨基萘 - 1 - 磺酰基（丹磺酰）IgE的第二个受体群体的反应（异源脱敏）。异源脱敏的程度取决于几个参数，包括第一种和第二种抗原的浓度以及各自IgE群体的密度。Ca²⁺反应的异源脱敏比脱颗粒反应的异源脱敏对第二种刺激物（丹磺酰 - 牛血清白蛋白）的浓度更敏感。激活GTP结合蛋白的AlF₄⁻可有效替代（DNP）2 - 抗生物素蛋白作为初始刺激剂和脱敏剂。其他动员细胞内Ca²⁺的试剂，包括凝血酶和Ca²⁺离子载体，在替代（DNP）2 - 抗生物素蛋白方面效果较差。因为用抗原预刺激不会使后续对AlF₄⁻或Ca²⁺离子载体的反应脱敏，所以似乎通过FcεRI的信号转导在早期步骤就受到损害。在（DNP）2 - 抗生物素蛋白交联后约10分钟内加入单价DNP半抗原，可完全阻止后续对丹磺酰 - 牛血清白蛋白的Ca²⁺或脱颗粒反应的脱敏。用DNP抗原孵育更长时间后，DNP半抗原在阻止丹磺酰 - 牛血清白蛋白反应脱敏方面的效果越来越差，即使DNP抗原的持续信号转导已停止。这些结果提示了一种对脱敏状态的细胞记忆形式。
