laboratory updates on igra testing · 2017. 8. 18. · 8/18/2017 4 tbi diagnosis two currently...

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EXCELLENCE EXPERTISE INNOVATION

LaboratoryUpdatesonIGRATesting

EdwardA.Graviss,PhD,MPH,FIDSAAugust18,2017

• No conflict of interests

• No relevant financial relationships with any commercial companies pertaining to this educational activity

EdwardA.Graviss,PhD,MPH,FIDSA,hasthefollowingdisclosurestomake:

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IGRAs in Clinical Practice - Update (Half Full and Half Empty)

Edward A. Graviss, PhD, MPH, [email protected]

Aker/Zvonkovic Photography

Conflict of Interest Statement

• Qiagen: PI initiated research; QFT-Plus assay tubes and kit donation

• Director of the Houston Methodist Hospital Molecular TB Laboratory: Perform both the QFT-GIT and T-SPOT.TB assays

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Objectives

• TB infection natural history and diagnosis

• Issues with IGRA Interpretation• With-in subject variability• High INF-γ responses • High conversion rates• Low mitogen values

• Overview of QFT-Plus: the future of QFT

• QFT-Plus: recent studies (published papers)

Natural History of TB Infection

Canadian Tuberculosis Standard, 7th edition, Chapter 2, 2014

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TBI Diagnosis

Two currently accepted methods for screening Mtb-exposed individuals for TB infection.

• TST – Tuberculin Skin Test

100+ years of experience, cheaper, more widely used worldwide

• IGRA - Interferon Gamma Release Assay

10+ years of experience, moderately expensive, used extensively in the developed world

− QuantiFERON

− T-SPOT.TB

Injection of PPD antigens below epidermal layer in vivo causes infiltration of antigen-specific lymphocytes and inflammatory cytokines

PBMCs from the peripheral blood are stimulated in vitro and production of INF-gammafrom sensitized T cells is measured by ELISA or ELISPOT

In-vitro and In-vivo Diagnostic Tests

Andersen P et al., Lancet 2000;356:1099-104

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TSTQuantiFERON-TB Gold

InTubeTSPOT.TB

Test Invasiveness

in vivo (skin test) in vitro (2.4 ml blood draw total)in vitro (≈ 4ml blood draw)

(possibly less for children, 1

compromised based on CBC)

Antigen UsedPPD

(a polyvalent antigen mixture –200+ antigens)

ESAT, CFP-10, TB7.7 (Mtb specific antigens)

ESAT, CFP-10 (Mtb specific antigens)

*Specificity97% in non-BCG vaccinated

60% in BCG vaccinated>95% in non-BCG vaccinated

(not affected by BCG vaccination)>95% in non-BCG vaccinated

(not affected by BCG vaccination)

*Sensitivity≈ 80%

(diminished in HIV+ and children)

≈ 80% (diminished in HIV+ and children)

≈ 90% (diminished in HIV+ and children)

Clinic Visits 2 1 1

Timing 48-72 hours 24-48 hours 24-48 hours

Error Possibility

High (manipulation and reading

errors)

Low – Mod : ELISA test (Pre-analytical sources)

Low : ELISPOT assay

BCG Boosting Effect

YesNo

(yes in TB infected)No

History 100+ years12 years

(FDA approved May 2005)9 years

(FDA approved July 2008)

* Pai M et al. Clin Microbiol Rev 2014; 27:3-20.

TST versus IGRA comparison

1) Cruz AT et al., Pediatrics. 2011 Jan;127(1):e31-8.

Issues with IGRA Result Interpretation

• Significant within-subject variability – at least 6 retrospective and prospective studies.

• High INFγ responses in the control unstimulated assay tube, “high nils”

• High IGRA conversion rates (4-7%) in serial tested health care workers when compared to historical or concurrent TST conversion rates (0.0-0.9%)

• Other Issues –

• Low mitogen values

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Metcalf JZ et al., AJRCCM 2013;187:206-11

Within-Subject VariabilityMetcalf JZ et al Am J Respir Crit Care Med. 2013; 187:206-211

543 consecutive patients with QFT ordered from 8/1/2010 – 7/31/2011, that had repeat testing per clinical lab’s SOP (>0.25 IU/mL)

Within-Subject Variability(Conversions and Reversions)

Metcalf JZ et al., AJRCCM 2013;187:206-11

543 eligible patients – 177 indeterminate = 366 positive and negative replicates

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Within-Subject Variability

Metcalf JZ, et al., AJRCCM 2013;187:206-11

• In this dataset a borderline TBI response was defined as a IFN-gamma concentration of 0.25-0.80 IU/mL

• For test results close to the 0.35 IU/ml cut–point, the normal within-subject variability = ±0.24 IU/mL

Palo Alto Study1: 0.35-0.72 IU/mL 80% risk of reversion

0.35-1.10 IU /mL 75% risk of reversion

1. Thanasssi W, et al., Pulm Med 2012; 291294

Sources of IGRA Variability

Pai, M., et al., Clin Microbiol Rev 2014; 27:3–20

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IGRA Sources of Variability –Effect on Assays


Agarwal S et al., Tuberculosis (Edinb) 2016; S92-S98.

• Levels of agreement differed between individual technicians and automated reader from moderate to very good

• Commercial ELISpot reader and manual counting have good agreement

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IGRA Sources of Variability –Effect on Assays


Serial Testing HCW – Seroconversions?

Conversionn/N (%)

Stable conversion

n (%)

Transient conversion

n (%)

TST 21/2293 (0.9) 1/12 (8) 11/12 (92)

QFT 138/2263 (6.1) 25/106 (24) 81/106 (76)

TSPOT 177/2137 (8.3) 27/118 (23) 91/118 (77)

Stable conversion: Change from Neg to Pos, followed by Pos test at next 6-month f/u

Transient conversion: Change from Neg to Pos, followed by Neg test at next 6-month f/u

Dorman SE, et al., AJRCCM 2014; 189: 77–87

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Summary Points: Conversions (1)

• Proportion of participants who underwent a “conversion” from negative to positive was higher when assessed by either IGRA than by the TST (7 – 9X)

• Approximately 75% of IGRA conversions were transient (after 6 months and no treatment)

• Compared with transient T-SPOT.TB converters, stable T-SPOT.TB converters had higher median (Ag-nil) values at conversion (10 vs 13) but there were other quantitative test results that differentiated stable vs transient converters

• Conversions (by any test method) were not associated with TB exposure variables assessed


Summary Points: Conversions (2)

• The likelihood of IGRA conversion increased as the baseline quantitative result increased toward the positivity cut-point, but proportionately few conversions were accounted for by individuals with baseline quantitative results just below the cut point.

• Test variability explained only a small proportion of apparent IGRA conversion (QFT: 5.2% – 7.5%; T-SPOT: 6.0% - 8.1%)

• In a sub-study in which QFT plasma were rerun immediately, half of the apparent conversions were not conversions on the re-runs

• Similar proportions of participants had IGRA “conversions” over intervals of 0 days, 2 weeks, and 6 months


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Conclusions• For BCG-vaccinated individuals, use of an IGRA at the time of

initial TBI testing will reduce the number of TBI diagnoses compared with using TST alone (the assumption is that IGRAS will correctly label as TBI-negative those people with a TST that is positive due to BCG sensitization, although there is no data is available support or refute this assumption)

• In this group of HCWs undergoing period TBI screening, a large % of apparent IGRA conversions did not represent a true change in biological status with respect to TB infection

• Strategies for discerning “true” vs “false” IGRA conversions are required; until then caution should be used in interpreting a single newly positive test in an individual with one or more prior negative tests • For QFT, doing repeat ELISA on the existing stimulated plasmas may

be helpful

• Repeating the IGRAs should be considered, although we did not formally assess this as a strategy


Graviss Lab Statistics (7/31/2017)

QFT Overall (+) – 13.26% (5149/38830)

QFT Overall (-) – 81.70% (31726/38830)

QFT Indeterminate – 5.03% (1955/38830)

All HMH Indeterminate – 25.27% (996/3942)

HMH TMC Only Indeterminate – 25.46% (712/2797)

T-Spot Overall (+) – 8.30% (1327/15997)

T-Spot Overall (-) – 83.78% (13402/15997)

T-Spot Borderline – 2.67% (427/15997)

T-Spot Fail – 5.23% (836/15997)

T-Spot No Test Performed – .03% (5/15997)

T-spot Fail excluding No Test Performed (n = 5) and Low Cell Count – 2.72% (423/15579)

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Overview of 4th generation IGRA –QuantiFERON-TB Gold Plus

QFT-Plus is FDA approved July 8, 2017. Package insert not available at current time.

Evolution of QFT TechnologyQuantiFERON-TB to QuantiFERON-TB Gold

1st Generation 2nd Generation 3rd Generation

QuantiFERON-TB Gold „In tube“

• 2007 U.S. FDA approval

• Scalable and easily automated

• Logistical advantage –remote incubation

• RD1 antigens and TB7.7 coated inside tubes

• >1300 peer reviewed publicatoins

QuantiFERON-TB Gold


• “Liquid antigen” version

• Antigens specific for M. tuberculosis complex organisms to measure cell-mediated immunity

• 99% specificity

• No cross reactivity with BCG

QuantiFERON-TB


• Measured cell-mediated immunity to the same tuberculin purified protein derivative (PPD) used for the tuberculin skin test (TST; M. avium)

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QuantiFERON-TB Gold Plus (QFT-Plus)

Desired characteristicsEnhanced performance

Improved performance in high-risk groups

Potential to provide additional clinical information

Harmonization of workflow options globally

• Increased sensitivity

• Sustained high specificity

• People who are immunocompromised

• People living with HIV/AIDS

• Risk-based algorithms

• Better to assist patient assessment and management

• 1-tube blood collection (optional)

• 4-point standard curve

Improve risk prediction?

QFT-Plus EU Package Insert

QFT In Tube QFT-Plus

Intended UseNo change

QFT is an in vitro diagnostic test using a peptide cocktail stimulating ESAT-6, CFP-10 proteins to stimulate cells in heparinized whole blood. Detection of interferon-γ (IFN-γ) by Enzyme-Linked Immunosorbent Assay (ELISA) is used to identify in vitro responses to these peptide antigens that are associated with Mycobacterium tuberculosis infection.

QFT is an indirect test for M. tuberculosis infection (including disease) and is intended for use in conjunction with risk assessment, radiography and other Medical and diagnostic evaluations.

Blood CollectionTubes

3 Tube test 4 Tube test

InterpretationOf Results Test value IU/mL

QFT result

TB-Nil (IU/ml) ≥0.35 Positive

Test value IU/mLQFT-Plus

result

TB1-Nil (IU/ml) ≥0.35 Positive

TB2-Nil (IU/ml) ≥0.35 Positive

Both TB1 - TB2-Nil (IU/ml) ≥0.35 Positive

LITHIUM HEPARIN SINGLE TUBE OPTION

Blood collected in single tube (5 mL)Transported at (22°C ± 5°C)

16 hrs to incubation timeTransferred to tube at lab

Control of pre-analytical error

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Differences between (QFT-GIT and QFT-Plus)

• Number of tubes used and volume (ideal volume) QFT-GIT = 3 tubes (CD4+) = 2.4 μL QFT-Plus = 4 tubes (CD4+ / CD8+) = 3.2 μL

• Polypeptides used in assays: QFT-GIT (ESAT-6Rv3874, CFP-10Rv3875, TB 7.7Rv3875c) QFT-Plus (ESAT-6Rv3874, CFP-10Rv3875)

• Size of polypeptides QFT-GIT: 20-mer (18pp with 10aa overlap) QFT-Plus: 20-mer in TB1; 20-mer and smaller in TB2

• ELISA Standards: Used for standard curves QFT-GIT: 26 pts with 2 sets of 8-standards QFT-Plus: 22 pts with 2 sets of 4-standards

New CD8+ antigens: Why?

CD8+ T cells and role in TB immunity

Mtb-specific CD8+ T cells secrete IFN and other soluble factors to (1–3):

• Suppress Mtb growth• Kill infected cells • Directly lyse intracellular Mtb

1. Immunology 1996; 87, 339. 2. Eur. J. Immunol. 2003; 33, 3293. 3. Science 1998; 282, 121.

https://news.brown.edu/articles/2014/10/immune

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CD8+ T cells and role in TB immunity

Biomarker for intracellular TB burden

TB-specific CD8+ T cells that produce IFN have been:• More frequently detected in those with active

TB disease vs. latent infection (4, 5)

• Associated with recent exposure to TB (6)

• Detectable in active TB subjects with HIV co-infection and young children (7, 8)

• Observed to decline when patients are exposed to anti-tuberculosis treatment (9)

4. J. Immunol. 2011; 187, 2222. 5. Eur. J. Immunol. 2013; 43, 1568. 6. Diagn. Microbiol. Infect. Dis. 2013; 75, 277. 7. J. Infect. 2014; 69, 533.8. Am. J. Respir. Crit. Care Med. 2012; 185, 206. 9. PLoS ONE 2014; 8, e81564. Epub.

QFT-Plus Clinical PerformancePublished Data

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First Independent Evaluation QFT-PLUS

Study design: Prospective multi-center study, 6 sites Italy and UK, enroll 11/2014–10/2015: 119 active TB cases; 106 low-risk controls,Non-BCG vaccinated pool; evaluated with QFT-PLUSSensitivity: 88% (102/116), 100% in subjects co-infected with HIV/TB (n=4) Specificity: 97% (103/106) Indeterminate: 1.3% (3/225) overall

Three indeterminates were from the active TB cohort (2.5% - 3/119)

Correlation with QFT-GIT (in a sub-cohort of 73 where QFT-GIT results were available): 94%

Barcellini L., et al. Eur Respir J. 2016;47:1587-90

Letter to the Editor

Barcellini et al., 2016 ERJ: Authors’ conclusions

Sensitivity Advantage• Sensitivity (88%) – which was higher than culture-confirmed active TB

patients in a 2011 meta-analysis for QFT-GIT (1)

CD8 Potential• Difference between TB2 and TB1 was higher in smear-positive

compared to smear-negative patients (significant difference). Magnitude of difference in agreement with flow studies (2)

Advantage in Immunosuppression• The increased IFNγ release by combined stimulation of CD4+ and

CD8+ T-cells observed in the TB2 antigen tube might be advantageous for improving the assay’s accuracy in patients with low CD4+ T-cell counts

1. Sester M, et al., Eur Respir J. 2011;37:100-1112. D’Ambrosio L et al., Eur Respir J. 2014; 43:1410-1420

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First evaluation of QuantiFERON-TB Gold Plus performance in contact screening1

Study design: Prospective recruitment of TST-positive adult contacts (TST ≥5 mm) at a single hospital in Milan

• Mean age = 39 (30-79).• 51.3% (n=61) non-European born, 78.8% (n=82) BCG vaccinated • 9.24% (n=11) were immunocompromised (HIV and other)• Contact screening based on NICE TB guidelines 2011 and Italian guidelines

1. Barcellini L et al., Eur Respir J. 2016; 48;14-11-1419

Barcellini et al, 2016: Results continued…

Overall agreement: ĸ = 0.8 (QFT-GIT vs QFT-Plus)Discordant results n=12

All 12 results were negative QFT-GIT and positive QFT-Plus

All but one discordant result had positive TST result >10 mm

Two conversions occurred with QFT-GIT upon retesting at 10–12 weeks, both initially positive by QFT-Plus

QFT-Plus had a stronger risk association (univariate analysis)

QFT-Plus showed a stronger risk association to aggregate exposure time than QFT-GIT (>12 hours/day): Odds ratio 14.8 QFT-Plus vs. 6.8 QFT-GIT.

QFT-Plus showed a stronger risk association to index case proximity than QFT-GIT (sleeping in the same room): Odds ratio vs. 5.6 QFT-Plus vs 4.0 QFT-GIT

Barcellini L et al., Eur Respir J. 2016; 48;14-11-1419

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Barcellini et al, 2016: Results continued…

TB2-TB1 differential as a surrogate measure for CD8+ stimulation

15% of 119 contacts had TB2-TB1 values >0.6 IU/mL

• Significantly associated with proximity to the index case (p = 0.0029)

• Significantly associated with European origin (p = 0.0453)

Barcellini et al, Eur Respir J. 2016 Jul 7. pii: ERJ-00510-2016. doi: 10.1183/13993003.00510-2016. Epub ahead of print]

Barcelleni L et al., Eur Respir J. 2016; 48;14-11-1419

“[QFT-Plus performance] suggests a role for the differential value between the TB2 and TB1 tubes as a proxy for recent infection.”

First characterization of the CD4+ and CD8+ T-cell responses to QuantiFERON-TB Plus

Study design: Prospectively enrolled 57 non-HIV pulmonary TB and TBI individuals within 7 days of treatment, at 1 site in Rome, Italy.

27 active TB = 23 culture positive and 4 clinically confirmed.

30 TBI = 18 remote contact (>3 years), 12 recent contact (<3m)

QFT-GIT, QFT-Plus and flow specimen drawn together

Goal: Evaluate by flow cytometry CD4+ and CD8+ responses to the Mtb antigens contained in the QFT-Plus.

Petruccioli, E, et al. J Infect 2016; 73:588-597

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Characterizing CD4/CD8 Response with Flow Data


CD4/CD8 Response with Disease Severity

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Petruccioli E. et al take home …• TB1 peptides were designed to stimulate CD4+ cells and TB2

designed to elicit CD4+ and CD8+ responses.

• CD8+ responses were seen following TB1 stimulation in a few folks (not all)

• TB2 CD8+ T-cell responses were associated with disease severity (radiologically)

• Across all evaluated groups TB2 CD8+ T-cell responses were associated with CD4 specific responses

• No association in the difference in INFγ production between TB2 and TB1, thus no differential CD8+ response.

• CD8+ T-cell responses are preferentially induced by TB2 which are mainly associated with active TB, thus potentially useful for CD4 impaired individuals

• Sensitivity of QFT-GIT and QFT-Plus are similar

Evaluation of QuantiFERON-TB Gold Plus for Detection of Mycobacterium tuberculosis

Infection in JapanLina T et al. Scientific Reports; 2016; 6:30617

Inferiority Study: QFT Plus vs QFT-GIT; multi-site (6 hospitals in Japan); 88% BCG+

Lina T. et al., Sci Reports; 2016; 6:30617

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Evaluation of QFT-Plus in Japan


Concentration of INFγ (IU/mL) measured using the different antigen-containing tubes in patients and in low-risk subjects

Different parameters calculated using the different antigen-containing tubes.

Evaluation of QFT-Plus in Japan

Results:• IFNγ concentration of QFT-Plus was lower than that

of QFT-GIT in TB patients (p < 0.001), but no difference in performance

• ROC curves showed both assays had AUC values over 0.99 without significant difference.

• QFT-Plus: sensitivity of 91.1% and specificity 97.6%

• QFT-Plus was as accurate as QFT-GIT despite a lack of TB7.7

• IFNγ values associated with age in QFT-GIT (p = 0.035) but not in QFT-Plus

• TB2 had significantly higher IFNγ concentrations compared TB1 (p < 0.001)


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Study design: Direct comparison study: QFT-GIT vs. QFT-Plus; single hospital in Munich, Germany. Consented HCWs – thru annual screening (n = 77) and TB suspects (n = 86) from 7/2015 –1/2016. Suspects = 24/86 (27.9%) culture confirmed; 33/86 (38.4%) clinical TB but 10/86 “post-specific” CXR anomalies.

Hoffman H et al., Clin Microbiol Infect; 2016; 22:702-703

Hoffmann H et al, 2016: Results continued…

• Pooled positive rates TB cases 89% compared to ~ 80% [1]

• Sensitivity rates similar between QFT-GIT and QFT-Plus

• Authors’ comment – “INFγ concentrations in QFT-GIT “significantly exceeded those measured in the TB1 tube though identical antigens used.”

1. Sester M et al Eur Respir J 2011; 37:100-11

9/163 = 5.5%

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Study design: Small cohort of migrant students, 11 QFT-GIT or QFT-Plus positive, 30 QFT-GIT and QFT-Plus negative – serial tested weekly over a month (4x); Lubeck, Germany between 2/2016 – 3/2016. Exposed students offered prophylaxis after r/o TB disease and 2 serial positive results.

Knierer et al., J Occ Med Toxicol 2017;12:1

QFT-Plus: a plus in variability? – Evaluation of New Generation IGRA in Serial Testing of Students with

a Migration Background in Germany

• A total of 163 serial measurements over a 4 week period - 41 students with 1 mis-draw.

• QFT-Plus: 4 conversions and 2 reversions

Conversion rate of 4.3% (4/93 possible conversions, 95% CI 1.4–11.3%)

Reversion rate of 6.9% (2/29 possible reversions, 95% CI 1.2–24.2%)

• QFT-G: 2 conversions and 1 reversion

Conversion rate: 2.2% (2 of 91, 95% CI 0.4–8.5%)

Reversion rate: 3.2% (1 of 31, 95% CI 0.2–18.5%)

• Agreement between the two IGRAs was 95.1% (κ = 0.89)

• Variance attributed to the individuals was low (QFT-Plus: ICC = 0.88)

QFT-Plus: a plus in variability? – Evaluation of New Generation IGRA in Serial Testing of Students with

a Migration Background in Germany

Knierer et al., J Occ Med Toxicol 2017;12:1

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Evaluation of QuantiFERON-TB Gold-Plus in Health Care Workers in a Low-Incidence Setting

Study design: Cross-sectional single-center study, Stanford Health Care Occ Health, enrollment :7/8/2015 – 11/15/2015; 989 random HCWs during annual and new employee TBI screening; Risk factor assessed via questionnaire; comparison of QFT-GIT and QFT-Plus

Moon H-W et al., J Clin Microbiol 2017;55:1650-1657

Positivity RateQFT-GIT = 4.3%QFT-Plus = 6.4%TB1 = 4.2%TB2 = 5.2%

Evaluation of QuantiFERON-TB Gold-Plus in Health Care Workers in a Low-Incidence Setting

Moon H-W et al., J Clin Microbiol 2017;55:1650-1657

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The Sensitivity of the QuantiFERON – TB Gold Plus in Zambian Adults with Active Tuberculosis

Study design: Consecutive AFB smear or Xpert positive pulmonary suspected TB patients, Lusaka, Zambia, enrollment :6/2015 – 3/2016; 108 adults. Blood drawn (2 days) prior to treatment in 1 LiHep tube transferred to lab within 8 hours of draw, risk factor assessed via methodology unknown (med rec, questionnaire?)

Telisinghe L. et al., Int J Tuberc Lung Dis 2017;21(6): 690-696

The Sensitivity of the QuantiFERON – TB Gold Plus in Zambian Adults with Active Tuberculosis

Telisinghe L. et al., Int J Tuberc Lung Dis 2017;21(6): 690-696

PLOS ONE 2008 3:e2489

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Study design: Cross-sectional (prevalent) study of 134 FB students and young professionals from high TB incidence countries 125:100,000; enrolled from 2 – 3/2016 in Lϋbeck, Germany. Goal: Estimate prevalence and risk factors of FB students/young professionals and compare results of QFT-GIT and QFT-Plus

5.2:100,000 (2012) ↑ 7.3:100,000 (2015); ↑ 1648 TB cases

No surveillance of universities - ↑ 236K FB students between 2014 and 2015

Self-admin risk questionnaire; QFT-GIT, QFT-Plus (via Li-heparin); IGRA positive = retest after 1 week

Gallegos-Morales et al., J Occ Med Toxicol 2017;12:12

• QFT-Plus positive = 11/134 (8.2%); QFT-Plus + QFT-GIT positive = 13/134 (9.7%) ; ĸ = 0.85

• 9 students positive by both assays; 2 QFT-GIT+/QFT-Plus -; 2 QFT-GIT -/GFT-Plus

• No TB cases identified

• No data on repeat draw (n = 11) other than: “positivity confirmed in at lest 1 of 2 IGRA test methods in all cases”

Gallegos-Morales: Results


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• Students in high burden countries have a high TBI prevalence (6.9% Rio – 45.1% in Uganda vet student; students in low burden countries have a low TBI prevalence (0.1% [med students – Italy], 2.1% [RN –Germany] and now students from High burden country in a low burden country setting (8.2% - Germany)

• High burden country = major risk factor for TB and higher risk of progression for TBI FB individuals

• Currently no regulations regarding TBI screening in immigrants nor students in Germany (ACHA association requires TBI screening for incoming students [2016]).

• Authors recommend risk questionnaire first then potential IGRA screening based on risks (e.g. targeted testing).

• Agreement good between QFT-GIT and QFT-Plus

Gallegos-Morales: Discussion


Summary: QuantiFERON-TB Gold Plus (QFT-Plus)

QFT-Plus: the latest evolution of QFT technologysame test principle-procedure as the QFT-GIT

QFT-Plus is an improved version of QFT-GIT :• Sensitivity of >95% in registration trials, lower in

published trials• Higher specificity of any test for TB infection, but

comparison to T-SPOT.TB unknown• Innovative CD8+ T-cell technology

– Optimized for CD4+ and CD8+ response– CD8 correlation to active TB, new infection and

burden of TB• One Li-Heparin tube draw for transfer into QFT-Plus

tubes

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Questions ?

HMH IGRA Lab

Justin Lew , BS Ngan Ha , BS

Sophie Im , BSKatie Ta , BS

Effect of Tuberculosis Treatment on Newly Developed QuantiFERON-TB® Gold Plus

Kamada, Arisu et al, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan P1174, 2016 ATS

• Significant decreases of interferon gamma responses were observed during treatment of active TB in both TB1 and TB2 tubes in the first 3 months.

• The delta (TB2-TB1) between tubes was statistically significant in the latter half and throughout treatment (P<0.05).

• The finding suggests CD8+ responses (represented by the difference between the 2 tubes) declined with TB treatment

N = 38 non-MDR TB patients (successfully treated)

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Compared coefficient of variation (CV) between the QFT-Plus and QFT

• 2 donors, one with TB infection and the other, without.

• 10 blood samples were drawn into the standard tubes from each subject (20 samples in total)

Statistical analysis: The coefficient of variation (CV) of each batch of subjects on each analyzer was calculated based on the mean value for TB antigen/TB1/TB2 minus the nil

Qualitative Results: Concordance - 100% and no indeterminate results Quantitative Results: QFT-Plus ELISA vs. QFT mean CV: 9.60% vs.18.25%

Discussion: There was no variation in qualitative results between the two assays; however, when looking at the in-batch quantitative data, the QFT-Plus CV was ~50% lower than QFT. Potential Impact – Reduction of reversions or conversions near the 0.35 IU/mL cut point

Gallagher D. et al., Eur Respir J 2016; 48: 953–954

Preliminary Data on the Precision of QFT-TB Plus Performance (In-house validation)

laboratory updates on igra testing · 2017. 8. 18. · 8/18/2017 4 tbi diagnosis two currently...

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