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Calcium activation of tissue transglutaminase in radioligand binding and enzyme-linked autoantibody immunoassays in childhood celiac disease.

Author:
  • Daniel Agardh
  • Bodil Roth
  • Åke Lernmark
  • Pål Stenberg
Publishing year: 2005
Language: English
Pages: 95-103
Publication/Series: Clinica Chimica Acta
Volume: 358
Issue: 1-2
Document type: Journal article
Publisher: Elsevier

Abstract english

Background



Conflicting data have been published concerning the effect of calcium on binding of autoantibodies to tissue transglutaminase (tTG) in celiac disease (CD).

Methods



IgA-tTG and IgG-tTG were measured with radioligand binding assays (RBA) using human recombinant (hr) 35S-tTG produced in lysate of rabbit reticulocytes and with guinea pig (gp) tTG ELISA in 51 CD children (median: 5.7 years) and 35 controls (median: 2.2 years). Assays were performed with and without calcium.

Results



In hr-tTG RBA, IgA-tTG levels remained unchanged after calcium detecting 50/51 CD children and 1/35 controls (p < 0.0001). IgG-tTG levels decreased with calcium (p < 0.0001) in CD children and detected 48/51 with and 49/51 without calcium as compared to 1/35 controls (p < 0.0001). In gp-tTG ELISA, levels increased with calcium (p < 0.0001) making it possible to detect an additional three to a total of 50/51 with IgA-tTG and 13 to 39/51 CD children with IgG-tTG compared to 4/35 and 8/35 controls (respectively, p < 0.0001). Rabbit reticulocytes displayed calcium-dependent tTG activity.

Conclusions



Calcium increased binding of IgA-tTG and IgG-tTG in the ELISA test. The reverse effect observed in RBA may be explained by competitive binding between calcium activated native rabbit reticulocyte tTG and hr 35S-tTG. tTG autoantibody assays may need taking calcium into account for accurate diagnostic sensitivity and specificity for CD.

Keywords

  • Clinical Laboratory Medicine
  • Calcium
  • Celiac disease
  • Radioimmunoassays
  • Tissue transglutaminase

Other

Published
  • Paediatric Endocrinology
  • Diabetes and Celiac Unit
  • Gastroenterology
  • ISSN: 0009-8981
E-mail: ake [dot] lernmark [at] med [dot] lu [dot] se

Principal investigator

Diabetes and Celiac Unit

+46 40 39 19 01

+46 70 616 47 79

60:11:015

Jan Waldenströms gata 35, Malmö

33

Lund University Diabetes Centre, CRC, SUS Malmö, Jan Waldenströms gata 35, House 91:12. SE-214 28 Malmö. Telephone: +46 40 39 10 00