Comparison of same day versus delayed enumeration of TB-specific T cell responses

Lenders, Laura; Meldau, Richard; Zyl-Smit, Richard van; Woodburne, Vivienne E; Maredza, Alice; Cashmore, Tamaryn J.; Semple, Patrick; Badri, Motasim; Zumla, Alimuddin; Dheda, Keertan

doi:10.1016/j.jinf.2010.01.012

Cited by 9 publications

(7 citation statements)

References 10 publications

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“…This study complements previous studies (1,5,11) showing that the TCX yields good results with extended storage times. Unlike Lenders et al (5), who showed less confident results at 32 h, we had the highest agreement rate at the 31-to 33-h time point, with a kappa of 0.97.…”

supporting

confidence: 89%

Validation of Increased Blood Storage Times with the T-SPOT. TB Assay with T-Cell Xtend Reagent in Individuals with Different Tuberculosis Risk Factors

et al. 2012

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We compared the performance of the T-SPOT.TB assay with blood used within 0 to 3.5 h after collection (control) to its performance with blood stored for 0 to 3.5, 5 to 8, 18 to 21, or 31 to 33 h with the addition of T-Cell Xtend (experimental), using samples from 154 participants. The 95.4% concordance between paired specimens indicated that blood can be stored for up to 33 h prior to T-SPOT.TB testing.

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supporting

confidence: 89%

Validation of Increased Blood Storage Times with the T-SPOT. TB Assay with T-Cell Xtend Reagent in Individuals with Different Tuberculosis Risk Factors

et al. 2012

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“…Smith et al, showed that delayed processing of ELISpot assays for M. tuberculosis lead to a reduction in spot forming units and Lenders et al, also showed a reduction in the conversion/reversion rate when the specimens were processed with the addition of the T-Cell Xtend ™ reagent however, this difference was not statistically significant. [12, 13] In our study, with the addition of T-Cell Xtend ™ reagent, there were no significant differences observed in the overall proportion of viable PBMCs or the total PBMC concentrations between blood stored for up to 8 hours and blood stored for 23–32 hours. Additional information regarding the T-Cell Xtend ™ reagent would have been gained by comparing the Tspot TB test to Tspot plus T-Cell Xtend ™ on Day one in our study.…”

Section: Discussionmentioning

confidence: 47%

Evaluation of a modified interferon-gamma release assay for the diagnosis of latent tuberculosis infection in adult and paediatric populations that enables delayed processing

Wang

Powell

Nagaraja

et al. 2010

Scandinavian Journal of Infectious Diseases

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The objective of the study was to evaluate the specificity of a modified interferon gamma release assay procedure that allows storage of blood samples for up to 32 hours before processing. A total of 116 subjects were enrolled for the study. Two blood samples were collected from each volunteer; one specimen was processed within 8 hours and analyzed using the T-SPOT.TB test; the second specimen was stored overnight and processed 23 to 32 hours later after addition of the T-Cell Xtend™ reagent and then analyzed using the T-SPOT.TB test. A total of 108 paired T-SPOT.TB and T-SPOT.TB plus T-Cell Xtend™ tests were analyzed on specimens from 97 adults and 11 children. The median age of the subjects was 28 years old with 68.5% female and 78.7% White. The overall agreement between the two tests was 98.2% (106/108). Specificity of the T-SPOT.TB test was 99.1% (107/108) and for T-SPOT.TB plus T-Cell Xtend was 97.2%. The two tests were comparable in results. Increasing storage time of the collected blood specimen prior to processing provides flexibility for clinicians and laboratories. Additional studies in larger and diverse patient populations including immunocompromised, pediatric, patients with active TB disease or latent tuberculosis infection are needed.

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“…Lenders et al studied the utility of T Cell Xtend, conducting T-SPOT. TB assays the same day as collection and approximately one and two days after collection [6]. Spot counts from 66 specimens T-SPOT.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, spot counts from 215 specimens assayed two days after collection with the T Cell Xtend reagent were similar to those processed on the day of collection. The T Cell Xtend reagent reduced the proportion of samples that changed from positive to negative and vice versa (4.54% to 2.83%), but this was not statistically significant [6]. Wang et al had similar high agreement (98.2%) among 108 specimens of results of immediate T-SPOT.…”

Section: Discussionmentioning

confidence: 99%

Maintenance of Sensitivity of the T-SPOT.TBAssay after Overnight Storage of Blood Samples, Dar es Salaam, Tanzania

Talbot

Maro

Ferguson

et al. 2012

Tuberculosis Research and Treatment

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Background. T-SPOT.TB is an interferon gamma release assay for detecting Mycobacterium tuberculosis infection. The requirement to process within 8 hours is constraining, deters use, and leads to invalid results. Addition of T Cell Xtend reagent may allow delayed processing, but has not been extensively field tested. Design. Consecutive AFB smear positive adult tuberculosis patients were prospectively recruited in Dar es Salaam, Tanzania. Patients provided a medical history, 1–3 sputum samples for culture and 1 blood sample which was transported to the laboratory under temperature-controlled conditions. After overnight storage, 25 μL of T Cell Xtend reagent was added per mL of blood, and the sample was tested using T-SPOT.TB. Results. 143 patients were enrolled: 57 patients were excluded because temperature control was not maintained, 19 patients were excluded due to red blood cell contamination, and one did not provide a sputum sample for culture. Among 66 evaluable patients, overall agreement between T-SPOT.TB and culture was 95.4% (95%CI; 87.1–99.0%) with Kappa value 0.548. Sensitivity of T-SPOT.TB when using T Cell Xtend reagent was 96.8% (95%CI; 88.8–99.6%). Conclusions. When T Cell Xtend reagent is added to specimens held overnight at recommended temperatures, T-SPOT.TB is as sensitive as the standard assay in patients with tuberculosis.

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Comparison of same day versus delayed enumeration of TB-specific T cell responses

Cited by 9 publications

References 10 publications

Validation of Increased Blood Storage Times with the T-SPOT. TB Assay with T-Cell Xtend Reagent in Individuals with Different Tuberculosis Risk Factors

Validation of Increased Blood Storage Times with the T-SPOT. TB Assay with T-Cell Xtend Reagent in Individuals with Different Tuberculosis Risk Factors

Evaluation of a modified interferon-gamma release assay for the diagnosis of latent tuberculosis infection in adult and paediatric populations that enables delayed processing

Maintenance of Sensitivity of the T-SPOT.TBAssay after Overnight Storage of Blood Samples, Dar es Salaam, Tanzania

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