To the Editors:
一个prior study has demonstrated that the rate of indeterminate T-SPOT®.TB(Oxford Immunotec, Abingdon, UK) test results performed under routine field conditions was low (3.4%) [1]。不确定的测试结果在年龄> 75岁的个体中更为常见,可能受运输条件(冬季寒冷的天气)的影响。由于这项研究发表了,因此引入了两项技术改进。首先是使用柠檬酸钠(Vacutainer®; BD,Franklin Lakes,NJ,USA)使用锂甲状腺素血液样品收集管而不是CPT™细胞制备管。另一个是使用T细胞Xtend™试剂(牛津免疫O)在样品中> 8小时[2]。
Meditest参考实验室(瑞士Lausanne)从瑞士的偏远地区接收血液样本,因此许多样品在进行分析之前过夜或≤36h。所有已收集到> 8 h的样品均用T细胞处理Xtend。因此,我们从2010年初开始对数据进行了更新的分析,以将不确定测试的速率与先前报告的测试进行比较。
使用T点分析了由Meditest收到的肝素化样品。TBtest according to the manufacturer’s instructions [3]。Samples >8 h old had 25 μL T-CellXtendreagent added per millitre of blood. The tube was inverted two to three times and incubated at room temperature for an additional 20 min before being processed in the T-SPOT.TB测定。
在2010年1月1日至3月31日之间,分析了445个样品。29%来自洛桑市,有44%来自当地地区(VAUD广州),瑞士偏远地区的27%。默认情况下,使用标准方法处理了同一天收到的本地地方的样本。在从区域收集地点收到的样品中,在194个中有38个被收到并在同一天(<8 h)进行处理,而第二天收到了156个。所有来自偏远地区的样本都通过邮政服务旅行过夜,并在收集血液后的12至36小时之间进行处理。使用T-Cell处理了从要求过夜运输的区域或偏远地区发送的样品Xtend。One sample was received >3 days after blood collection and was excluded from the analysis, leaving 444 samples for the final interpretation (table 1).
六个样本来自年轻患者(6-15岁;全阴性),34例来自老年患者(> 65岁),而所有其他患者则来自16至65岁的成年人。256(57%)样本来自男性。很小或非常老的患者没有测试结果不确定。
The rate of positivity for the samples from Lausanne, Vaud and remote places was 10, 17 and 10%, respectively. Nine tests were borderline (having five, six or seven more spots than the nil control) and one was indeterminate (from a remote location). This subject was tested again 1 month later and was again indeterminate. On both occassions, there were >10 spots in the nil control. The subject was an adult between 16 and 65 yrs of age.
使用T点获得的不确定结果的速率。TB在现场条件下进行的先前研究中,测定已经很低[1], was reduced to an even lower value (one out of 444; 0.2%). The only indeterminate result was sent from a remote place and remained indeterminate after repeat processing. We therefore assume that this subject had some abnormality in their lymphocyte function. Interestingly, there were no indeterminate results in samples sent from local sources. The decline in indeterminate results in this group compared to the previous study may be due to the exclusive use of lithium heparinate blood tubes instead of Vacutainer CPT tubes. We assume that the survival of the lymphocytes may be altered by the CPT tube content (citrate), particularly during transport, with partial separation and resuspension of cells, whereas the lymphocytes are more stable in a plain lithium heparinate tube, where the separation takes place only once the tubes are in the laboratory. If we consider only the samples sent from regional or remote sources, the rate of indeterminate test result is still very low (one out of 317; 0.3%). The use of T-CellXtend对所有样本运送隔夜甲型肝炎e had a beneficial effect on older samples. The cold weather conditions had no influence on the rate of indeterminate results (all samples were sent and processed in winter). The number of tests performed in very young or very old patients being small, we cannot assess the rate of indeterminate in these population groups.
来自沃德县的样本中的阳性率略高(17%,versus10% in other groups) can be explained since these samples were mostly from recent immigrants from countries with a high prevalence of tuberculosis, whereas the samples from the city or from remote places were more often taken for contact tracing investigations where the rate of infection may be expected to be lower.
In conclusion, these results demonstrate that the use of lithium heparinate blood collection tubes for all samples and T-CellXtend对于运输的样品,一夜之间可以处理瑞士各地的样品,同时尽管旅行时间更长(8-36 h),但仍保持不确定测试结果的速度非常低。根据我们的经验,在某些免疫异常并且不代表实验室衰竭的患者中观察到唯一不确定的测试结果。
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- ©ERS 2011