Open AccessThe performance of T‐cell Xtend reagent in increasing blood storage times for interferon gamma release assays
Author(s) -
Li Junlian,
Liu Yan,
Ma Liyamu,
Gu Libike,
Wang Quan,
Xu Miao,
Ma Ruiying,
Zhang Yali,
Yang Zhenping,
Deng Junjie,
Yi Xing
Publication year - 2018
Publication title -
journal of clinical laboratory analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 50
eISSN - 1098-2825
pISSN - 0887-8013
DOI - 10.1002/jcla.22253
Subject(s) - medicine , concordance , population , tuberculosis , white blood cell , whole blood , gastroenterology , immunology , peripheral blood , peripheral blood mononuclear cell , surgery , pathology , in vitro , biology , biochemistry , environmental health
Background T‐cell Xtend ( TCX ) was introduced to extend the blood storage time for T‐ SPOT . TB test, a widely used commercial interferon gamma release assay ( IGRA ) for rapid in vitro tuberculosis. Methods A total of 99 Uyghur suspected tuberculosis patients were recruited in this study. T‐ SPOT . TB test was performed with fresh blood (controls), 36 hours delayed blood and delayed and TCX ‐treated (at 36 hours) blood from each patient, respectively. Results White blood cells and lymphocytes proportion in peripheral blood mononuclear cells s and spot‐forming cells in positive control wells decreased significantly in delayed blood samples when compared with controls, while this decrease was not detected in TCX ‐treated group. In the 58 patients with paired T‐ SPOT . TB results of three groups of samples, a higher positive rate was observed in TCX ‐treated group than both in controls and untreated group (41.4% vs 37.9% and 25.9%). The concordance of T‐ SPOT . TB results between the treated group and controls was 0.856, whereas the agreement between controls and untreated group was unsatisfactory (0.649). In the 23 elderly patients (>70 years old) with paired T‐ SPOT . TB results of controls and TCX group, treated group showed a non‐significant trend toward higher positive rate than controls (43.5% vs 26.1%, P =.22). Meanwhile, TCX treatment reduced the risk of false negative T‐ SPOT . TB results in the elderly population. Conclusion Deterioration of blood sample caused by long storage time can be neutralized by TCX treatment. The results provide data for the utility of TCX in a novel population and in Asian region, and reveal the potential of TCX to improve the accuracy of T‐ SPOT . TB test in elderly population.