Improving the Timeframe Between Blood Collection and Interferon Gamma Release Assay Using T-Cell Xtend
Journal of Infection (2011) xx, 1e7
www.elsevierhealth.com/journals/jinf
Improving the timeframe between blood collection and interferon gamma release assay using T-Cell XtendÒ
J.J.M. Bouwman a,*, S.F.T. Thijsen a, A.W. Bossink b a b
Department of Medical Microbiology and Immunology, Diakonessen Hospital Utrecht, The Netherlands Department of Pulmonology, Diakonessen Hospital, Utrecht, The Netherlands
Accepted 9 October 2011
T-Cell XtendÒ; TSPOT.TBÒ; Lithium heparin; IGRA; Interferon gamma; Tuberculosis
KEYWORDS
Summary Vacutainer CPT tubes require blood samples for TSPOT.TB to be processed within 8 h. In this study we evaluated the ability of T-Cell Xtend to maintain the number and function of lymphocytes after 24 and 48 h of blood storage, giving similar test results as in freshly isolated specimens. Methods: Whole blood specimens from 59 individuals were collected in Vacutainer CPT tubes (CPT) and lithium heparin (LH) tubes. CPT tubes were processed within 8 h. T-Cell Xtend was added to LH tubes after 24 or 48 h. We also left LH tubes untreated for 48 h. Total number of white blood cells (WBC) and proportions of lymphocytes and granulocytes were determined in the isolated Peripheral Blood Mononuclear Cells (PBMC). We also evaluated the performance of T-Cell Xtend in the TSPOT.TB assay. Results: PBMC yields from T-Cell Xtend treated LH samples did not differ from PBMC yields from CPT tubes, but T-Cell Xtend had a pronounced effect on the proportions of lymphocytes and granulocytes. The mean lymphocyte percentage in PBMCs isolated from fresh CPT blood was 84.31 Æ 1.14% (at t Z 48 h), but was decreased to 52.72 Æ 3.34% (p < 0.05) in untreated LH blood (at t Z 48 h). This effect was neutralized by T-Cell Xtend (85.44 Æ 0.74%). We observed a similar but opposite effect on granulocytes: The mean proportion in untreated LH blood was increased to 40.9 Æ 3.67% (p < 0.001) compared to CPT blood (8.26 Æ 0.89%). Treatment of LH samples with T-Cell
www.elsevierhealth.com/journals/jinf
Improving the timeframe between blood collection and interferon gamma release assay using T-Cell XtendÒ
J.J.M. Bouwman a,*, S.F.T. Thijsen a, A.W. Bossink b a b
Department of Medical Microbiology and Immunology, Diakonessen Hospital Utrecht, The Netherlands Department of Pulmonology, Diakonessen Hospital, Utrecht, The Netherlands
Accepted 9 October 2011
T-Cell XtendÒ; TSPOT.TBÒ; Lithium heparin; IGRA; Interferon gamma; Tuberculosis
KEYWORDS
Summary Vacutainer CPT tubes require blood samples for TSPOT.TB to be processed within 8 h. In this study we evaluated the ability of T-Cell Xtend to maintain the number and function of lymphocytes after 24 and 48 h of blood storage, giving similar test results as in freshly isolated specimens. Methods: Whole blood specimens from 59 individuals were collected in Vacutainer CPT tubes (CPT) and lithium heparin (LH) tubes. CPT tubes were processed within 8 h. T-Cell Xtend was added to LH tubes after 24 or 48 h. We also left LH tubes untreated for 48 h. Total number of white blood cells (WBC) and proportions of lymphocytes and granulocytes were determined in the isolated Peripheral Blood Mononuclear Cells (PBMC). We also evaluated the performance of T-Cell Xtend in the TSPOT.TB assay. Results: PBMC yields from T-Cell Xtend treated LH samples did not differ from PBMC yields from CPT tubes, but T-Cell Xtend had a pronounced effect on the proportions of lymphocytes and granulocytes. The mean lymphocyte percentage in PBMCs isolated from fresh CPT blood was 84.31 Æ 1.14% (at t Z 48 h), but was decreased to 52.72 Æ 3.34% (p < 0.05) in untreated LH blood (at t Z 48 h). This effect was neutralized by T-Cell Xtend (85.44 Æ 0.74%). We observed a similar but opposite effect on granulocytes: The mean proportion in untreated LH blood was increased to 40.9 Æ 3.67% (p < 0.001) compared to CPT blood (8.26 Æ 0.89%). Treatment of LH samples with T-Cell