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Calcium activation of tissue transglutaminase in radioligand binding and enzyme-linked autoantibody immunoassays in childhood celiac disease.
Clin Chim Acta. 2005 Aug; 358(1-2):95-103.CC

Abstract

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) (35)S-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 (35)S-tTG. tTG autoantibody assays may need taking calcium into account for accurate diagnostic sensitivity and specificity for CD.

Authors+Show Affiliations

Department of Pediatrics, University Hospital MAS, Lund University, S-205 02, Malmö, Sweden. daniel.agardh@home.seNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15946660

Citation

Agardh, Daniel, et al. "Calcium Activation of Tissue Transglutaminase in Radioligand Binding and Enzyme-linked Autoantibody Immunoassays in Childhood Celiac Disease." Clinica Chimica Acta; International Journal of Clinical Chemistry, vol. 358, no. 1-2, 2005, pp. 95-103.
Agardh D, Roth B, Lernmark A, et al. Calcium activation of tissue transglutaminase in radioligand binding and enzyme-linked autoantibody immunoassays in childhood celiac disease. Clin Chim Acta. 2005;358(1-2):95-103.
Agardh, D., Roth, B., Lernmark, A., & Stenberg, P. (2005). Calcium activation of tissue transglutaminase in radioligand binding and enzyme-linked autoantibody immunoassays in childhood celiac disease. Clinica Chimica Acta; International Journal of Clinical Chemistry, 358(1-2), 95-103.
Agardh D, et al. Calcium Activation of Tissue Transglutaminase in Radioligand Binding and Enzyme-linked Autoantibody Immunoassays in Childhood Celiac Disease. Clin Chim Acta. 2005;358(1-2):95-103. PubMed PMID: 15946660.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Calcium activation of tissue transglutaminase in radioligand binding and enzyme-linked autoantibody immunoassays in childhood celiac disease. AU - Agardh,Daniel, AU - Roth,Bodil, AU - Lernmark,Ake, AU - Stenberg,Pål, PY - 2004/12/20/received PY - 2005/02/09/revised PY - 2005/02/09/accepted PY - 2005/6/11/pubmed PY - 2005/12/16/medline PY - 2005/6/11/entrez SP - 95 EP - 103 JF - Clinica chimica acta; international journal of clinical chemistry JO - Clin. Chim. Acta VL - 358 IS - 1-2 N2 - 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) (35)S-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 (35)S-tTG. tTG autoantibody assays may need taking calcium into account for accurate diagnostic sensitivity and specificity for CD. SN - 0009-8981 UR - https://www.unboundmedicine.com/medline/citation/15946660/Calcium_activation_of_tissue_transglutaminase_in_radioligand_binding_and_enzyme_linked_autoantibody_immunoassays_in_childhood_celiac_disease_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0009-8981(05)00207-X DB - PRIME DP - Unbound Medicine ER -