British Columbia Children's Hospital Research Institute, Rm A4-145, 950 West 28th Ave, Vancouver, BC, V5Z 4H4, Canada.
Centre for Blood Research, The University of British Columbia, Vancouver, BC, Canada.
Pediatr Rheumatol Online J. 2020 Jul 10;18(1):54. doi: 10.1186/s12969-020-00446-5.
Human adenosine deaminase 2 (ADA2) is an extracellular enzyme that negatively regulates adenosine-mediated cell signaling by converting adenosine to inosine. Altered ADA2 enzyme activity has been associated with some viral infections and rheumatic diseases. The potential utility of ADA2 as a biomarker is, however, limited by the absence of established ranges of ADA2 concentration and enzyme activity in the healthy population. It is known that ADA2 enzyme activity is lower in adults, but when (and why) this decline happens is not known. The purpose of this study was to establish normative ranges of ADA2 enzyme activity and protein concentration in the healthy pediatric population.
We modified a commercially available ADA2 enzyme activity assay to enable higher throughput analysis of fresh, frozen and hemolyzed blood samples. With this assay and ADA2 protein immunoblotting, we analyzed ADA2 enzyme activity and protein concentration in blood plasma from a cohort of children and adolescents (n = 94) aged 5 months to 18 years. One-way ANOVA with subsequent Tukey multiple comparison test was used to analyze group differences. Reference intervals were generated using the central 95% of the population (2-97.5 percentiles).
ADA2 enzyme activity was consistent in fresh, frozen, and hemolyzed sera and plasma as measured by our modified assay. Analysis of plasma samples from the healthy pediatric cohort revealed that ADA2 enzyme activity is significantly lower in older children than in younger children (p < 0.0001). In contrast, there was no significant correlation between ADA2 protein concentration and either age or ADA2 enzyme activity.
We observed that ADA2 enzyme activity, but not ADA2 protein concentration, negatively correlates with age in a cohort of children and adolescents. Our findings stress the importance of appropriate age-matched controls for assessing ADA2 enzyme activity in the clinical setting.
人类腺苷脱氨酶 2（ADA2）是一种细胞外酶，通过将腺苷转化为肌苷来负调控腺苷介导的细胞信号转导。ADA2 酶活性的改变与一些病毒感染和风湿性疾病有关。然而，由于缺乏健康人群中 ADA2 浓度和酶活性的既定范围，ADA2 作为生物标志物的潜在用途受到限制。已知 ADA2 酶活性在成人中较低，但这种下降发生的时间（以及原因）尚不清楚。本研究的目的是确定健康儿科人群中 ADA2 酶活性的正常范围。
我们修改了一种商业上可用的 ADA2 酶活性测定法，以实现对新鲜、冷冻和溶血血液样本的高通量分析。使用该测定法和 ADA2 蛋白免疫印迹法，我们分析了 94 名年龄在 5 个月至 18 岁的儿童和青少年血液血浆中的 ADA2 酶活性和蛋白浓度。使用单向方差分析（ANOVA）和随后的 Tukey 多重比较检验分析组间差异。参考区间采用人群中位数的 95%（2-97.5%分位数）生成。
我们的改良测定法显示，ADA2 酶活性在新鲜、冷冻和溶血血清和血浆中保持一致。对健康儿科队列的血浆样本分析表明，ADA2 酶活性在年龄较大的儿童中明显低于年龄较小的儿童（p<0.0001）。相比之下，ADA2 蛋白浓度与年龄或 ADA2 酶活性之间没有显著相关性。
我们观察到在儿童和青少年队列中，ADA2 酶活性（但不是 ADA2 蛋白浓度）与年龄呈负相关。我们的研究结果强调了在临床环境中评估 ADA2 酶活性时，使用年龄匹配对照的重要性。
