SELF TRANSGLUT RAPID COELIAC ANT BY LATERAL F

Ilma Korponay Szabó

1,2

, Tiina Raivio

2

, Pekka Collin

3

, Kaija

1

University of Debrecen, Debrecen, Centre and Dept. of

3

Internal Medicine, Finland,

4

Heim Pál Children’s

Coeliac Disease Study Group

AMINASE-BASED IBODY DETECTION LOW METHOD

Katri Kaukinen

3

, Judit B.Kovács

4

, Laurila

2

, Markku Mäki

2

Hungary,

2

Paediatric Research University of Tampere, Tampere, Hospital, Budapest, Hungary

Coeliac Disease Study Group

Coeliac Disease Study Group

BACKGROUND AND AIMS

• Circulating antibodies against type-2(tissue) tansglutaminase (TG) are characteristic activity markers of gluten-sensitive enteropathy. Their detections is an important diagnostic tool in finding new patients and evaluating treatment efficacy. • Antibodies against TG are currently measured in specialised laboratories using ELISA or immunofluorescent method (endomysial antibody test, EMA). The testing is expensive and patients and doctors have to wait for the results.

Future

→

quick, easy to perform, economical and widely accessible coeliac tests

• AIM of this study was to develop and evaluate a rapid inexpensive test for the use in the doctor’s office, at the bedside or in the home of the patients.

Coeliac Disease Study Group

PRINCIPLE OF THE TESTING

TG Haemolysis Whole blood samples contain self-TG antigen inside normal red blood cells.

RBC self-TG can be used as antigen to detect anti-TG antibodies if present in the plasma of the same sample. TG Label (anti-IgA) TG Formation of self-TG/anti-TG complexes TG Lateral flow

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TG TG TG Capture of the labelled complexes by TG-binding protein line

The lateral flow system

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PATIENTS

• Samples from 109 subjects on normal diet 55 untreated patients with Clinical diagnoses of the controls coeliac disease diagnosed according to the ESPGHAN Dyspepsia 37 criteria (32 children, 23 adults) GOR 5 age: 1,8-69 years IBD 3 54 disease controls with normal Cong. sucrase deficiency 3 mucosa at jejunal biopsy (23 children, 31 adults) FAP 2 age: 2,6-72 years Recurrent abdominal pain 2 All control subjects were negative for EMA.

• Samples on a gluten-free diet for one year obtained from 11 of the coeliac patients Swachman-Diamond sy Nonspecific rash All 1 1 54

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METHODS

• The rapid antibody test based on the use of self-TG antigen was developed into a lateral flow system. • Initial evaluation was carried out with whole blood samples anticoagulated with EDTA or citrate.

• Results were read after 5 minutes by a blinded observer who was unaware of the clinical status of the patients.

• Lateral flow results were compared with the laboratory detection of coeliac antibodies from serum collected at the same time. – TG antibody ELISA (Celikey™, Pharmacia, cut-off 5 U/ml) – EMA: indirect immunfluorescent method on monkey oesophagus (serum dilution 1:2.5)

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TEST RESULT

(at 5 minutes) Positive Negative Coeliac antibody detection Control line

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RESULTS

• 53 out of the 55 samples from untreated coeliac patients were positive (96.4 %) at 5 minutes with lateral flow. Most samples were clearly positive already at one minute after application of the sample.

• Three of the 54 controls showed a positive result, and 4 additional controls showed a very faint line at the test area. Lateral flow rapid test Sensitivity 96.4 % Specificity 87.0 %

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Comparison of lateral flow test results with conventional laboratory tests

100

92% EMA+ Lateral flow+ 53 Lateral flow 2 EMA Total

100

92% 7 60 Lateral flow+ TG-Ab+ 53 47 49 Lateral flow 2 TG-Ab- 7 47 Total 60

Coeliac Disease Study Group

49 Concordant test results with EMA/ELISA (red): 92% of all untreated samples

100,0 Comparison of lateral flow test results before and on a gluten-free diet Nine of the 11 coeliac patients reevaluated after one year on diet had negative lateral flow test result. 10,0 The two patients still positive had TG antibody ELISA levels near the cut-off (4.6 and 4.2 U/ml).

1,0 Before diet

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After diet positive lateral flow negative lateral flow

ADVANTAGES

• Results are available within 5 minutes onsite.

• The testing is simple, cheap and easy-to perform from capillary blood.

• No recombinant / purified TG2 antigen is needed.

• No laboratory equipment is needed.

• No blood centrifugation is needed.

Coeliac Disease Study Group

CONCLUSIONS

• The self TG-based rapid coeliac antibody test is comparably sensitive as EMA and TG antibody detection by ELISA.

• The rapid test is able to show the clearence of antibodies (seroreversion) on a gluten free diet.

• Immediate availability of results may help physicians to speed up the diagnostic process and to evaluate dietary compliance.

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POTENTIAL APPLICATIONS

of coeliac antibody detection at the point of care  Case finding among symptomatic patients in the office or at the bedside  Screening of at-risk groups •

family members, autoimmune patients, pregnant women etc.

 Population screening studies  Diet monitoring in the office or at home

Coeliac Disease Study Group