Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
Division of Medical and Chemical Laboratory Diagnostics, Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria.
Int J Immunopathol Pharmacol. 2020 Jan-Dec;34:2058738420954945. doi: 10.1177/2058738420954945.
During human diamine oxidase (DAO) ELISA development we noticed that in serum DAO concentrations appear to be higher when compared to plasma. Neutrophils contain DAO in the specific granules and we hypothesized that DAO is released from neutrophils during serum coagulation. If activation of neutrophils can release DAO, its concentrations might be elevated in vivo after lipopolysaccharide (LPS) administration and in bacteremic patients. Using blood from healthy volunteers DAO concentrations were measured ex vivo in serum, citrate, EDTA and heparin plasma over several hours and after activation of neutrophils. Lipopolysaccharide and granulocyte-colony stimulating factor (G-CSF) were administered to 15 and 8 healthy volunteers, respectively and DAO concentrations were measured at different timepoints. DAO antigen levels were also determined in three different subcohorts of patients with culture-proven bacteremia and high C-reactive protein (CRP) levels. DAO concentrations were elevated in a time-dependent manner in serum but not in EDTA or citrate plasma ( < 0.01). Neutrophil activation using phorbol myristate acetate (PMA) and zymosan dose-dependently caused DAO concentrations to be elevated more than 10-fold at both 22°C and 37°C (both -values <0.001). Administration of LPS to healthy volunteers released DAO from neutrophils ( < 0.001). Of the 55 different bacteremic patients selected from three independent cohorts only 3 (5.4%) showed highly elevated DAO concentrations. Serum DAO concentrations do not accurately reflect circulating enzyme levels but coagulation-induced neutrophil activation and consequently DAO release. Only a few bacteremic patients show high DAO concentrations able to degrade histamine rapidly.
在人类二胺氧化酶（DAO）ELISA 开发过程中，我们注意到血清中的 DAO 浓度似乎比血浆中的高。中性粒细胞含有 DAO 的特异性颗粒，我们假设 DAO 在血清凝固过程中从中性粒细胞中释放出来。如果中性粒细胞的激活可以释放 DAO，那么在体内给予脂多糖（LPS）和菌血症患者后，其浓度可能会升高。使用健康志愿者的血液，我们在几个小时内和中性粒细胞激活后，分别在血清、柠檬酸盐、EDTA 和肝素血浆中测量了离体的 DAO 浓度。给 15 名和 8 名健康志愿者分别给予 LPS 和粒细胞集落刺激因子（G-CSF），并在不同时间点测量 DAO 浓度。还在三个不同亚组的经培养证实有菌血症和高 C 反应蛋白（CRP）水平的患者中测定了 DAO 抗原水平。DAO 浓度在血清中呈时间依赖性升高，但在 EDTA 或柠檬酸盐血浆中则没有升高（ < 0.01）。使用佛波醇肉豆蔻酸乙酯（PMA）和酵母聚糖激活中性粒细胞，在 22°C 和 37°C 时，DAOO 浓度均升高了 10 多倍（均 -值 <0.001）。给健康志愿者给予 LPS 可从中性粒细胞中释放 DAO（ < 0.001）。从三个独立队列中选择的 55 名不同菌血症患者中，只有 3 名（5.4%）表现出高度升高的 DAO 浓度。血清 DAO 浓度不能准确反映循环酶水平，但会引起凝血诱导的中性粒细胞激活和随后的 DAO 释放。只有少数菌血症患者表现出能够快速降解组氨酸的高 DAO 浓度。
