Covalent binding of the nitroso metabolite of sulfamethoxazole leads to toxicity and major histocompatibility complex-restricted antigen presentation
Covalent binding of the nitroso metabolite of sulfamethoxazole leads to toxicity and major histocompatibility complex-restricted antigen presentation
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DOI：
10.1124/mol.62.3.628
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发表时间：
2002-09-01
影响因子：
3.6
通讯作者：
Park, BK
中科院分区：
文献类型：
--
作者：
Naisbitt, DJ;Farrell, J;Park, BK
磺胺甲恶唑（SMX）治疗可导致超敏反应。来自过敏患者的T细胞识别母体药物和/或反应性亚硝基（SMX-NO）代谢物。在本研究中，我们采用一种新的体外大鼠脾细胞试验，研究了SMX-NO对细胞表面半抗原化的毒理学和免疫学后果。自发转化产生了大量的SMX-羟胺、硝基-SMX，和以前未知的偶氮氧基和偶氮二聚体在15分钟内。SMX-NO与细胞蛋白的不可逆结合通过流式细胞术证明，在抗原呈递细胞表面上的半抗原化比在T细胞上的大。SMX-NO的不可逆结合的后果以两种方式进行了检查。首先，高于阈值水平的半抗原化导致细胞死亡（凋亡和坏死）成比例增加。事实上，变得半抗原化的细胞与经历坏死性细胞死亡的细胞是相同的。第二，致敏的脾细胞增殖的主要组织相容性复合体（MHC）限制性抗原的存在下，来自活细胞和死细胞半抗原与低和高水平的SMX-NO，分别。然而，SMX-NO对MHC的直接修饰不是抗原提呈的机制。SMX-NO对T细胞增殖和毒性的抗原阈值估计分别在0.5至1 μ M和5至10 μ M之间。SMX-NO产生有效抗原和引起细胞毒性的潜力可以组合提供诱导对SMX的超敏反应所必需的信号。
Treatment with sulfamethoxazole (SMX) can lead to hypersensitivity reactions. T cells from hypersensitive patients recognize either the parent drug and/or the reactive nitroso (SMX-NO) metabolite. In this study, using a novel in vitro rat splenocyte assay, we have investigated the toxicological and immunological consequences of cell surface haptenation by SMX-NO. SMX-NO was found to be unstable in solution; spontaneous transformation yielded appreciable amounts of SMX-hydroxylamine, nitro-SMX, and the previously unknown azoxy and azo dimers within 15 min. Irreversible binding of SMX-NO to cellular protein was demonstrated by flow cytometry, with haptenation being greater on the surface of antigen-presenting cells than on T cells. The consequences of irreversible binding of SMX-NO were examined in two ways. First, haptenation above a threshold level led to a proportionate increase in cell death (both apoptosis and necrosis). Indeed, the cells that became haptenated were the same as those that underwent necrotic cell death. Second, sensitized splenocytes proliferated in the presence of major histocompatibility complex (MHC)-restricted antigen derived from both viable and dead cells haptenated with low and high levels of SMX-NO, respectively. However, direct modification of MHC by SMX-NO was not the mechanism of antigen presentation. The antigenic threshold of SMX-NO for T-cell proliferation and toxicity was estimated to be between 0.5 and 1 muM and 5 to 10 muM, respectively. The potential of SMX-NO to generate a potent antigen and cause cytotoxicity may in combination provide the signals necessary to induce a hypersensitivity reaction to SMX.