TCRβ Clonality Improves Diagnostic Yield of TCRγ Clonality in Refractory Celiac Disease

Celiac.com 04/02/2012 - A team of researchers recently set out to assess diagnostic yield of Vβ and Vγ clonality in refractory celiac disease (RCD). The team set out to verify whether analyzing both TCRβ and TCRγ clonality in duodenal biopsies from RCD patients improves diagnostic accuracy.

The research team included Vittorio Perfetti, Laura Brunetti, Federico Biagi, Rachele Ciccocioppo, Paola I. Bianchi, and Gino R. Corazza. They are affiliated with the Coeliac Centre/First Department of Internal Medicine, and the Department of Medical Oncology at the Fondazione IRCCS Policlinico San Matteo of the University of Pavia in Italy.

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Refractory celiac disease is what is known as a pre-neoplastic condition, because many patients develop a kind of cancer called enteropathy-type T-cell lymphoma, which is a mature T-cell receptor α-β lymphoma that forms in the gut, and is often fatal.

Recent research has been directed at a variety of intraepithelial intestinal lymphocytes. Polymerase chain reaction (PCR) analysis and sequencing shows that these lymphocytes both express the same lymphoma T-cell receptor variable region (V)γ.

Also, the Biomedicine and Health-2 Concerted Action has created standardized, highly specific, and sensitive PCR assays for both Vγ and Vβ.

The team set out to verify whether analyzing both rearrangements in duodenal biopsies from RCD patients increases the diagnostic accuracy of this method.

For the study, the team analyzed duodenal biopsies from 15 RCD patients, 21 negative controls, and 2 positive controls with enteropathy-type T-cell lymphoma complicating celiac disease.

The them conducted multiplex clonality analyses using Biomedicine and Health-2 protocols. They cloned and sequenced PCR products.

They found monoclonal rearrangements in 5/15 samples from patients with RCD, two of which showed both rearrangements, two which showed Vβ, and just one Vγ clonality.

Monoclonality was found in 4/8 of the RCD patients who subsequently died, whereas only 1/7 of the patients still alive presented a monoclonal rearrangement. Positive controls revealed both monoclonal rearrangements; rearrangements were not detected in 20 of 21 negative controls. Sequencing of the amplified fragments confirmed the results.

Results showed that the combined analysis of both TCRβ and TCRγ rearrangements allowed recognition of monoclonal populations in patients who otherwise tested negative. Overall detection rates increased from 20%(Vγ only) to 33%(Vγ and Vβ),

Increasing detection in patients who would otherwise test negative increases chances of early identification of RCD patients at high risk of death.

Source:

• J Clin Gastroenterol. 2012 Jan 30.