# A laboratory test to detect gliadin-specific CD4+ T-cells for difficult to diagnose celiac disease

## TL;DR

A new lab test detects gluten-sensitive T-cells in blood to help diagnose celiac disease in difficult cases.

## Contribution

A simplified flow cytometry method using dextramers to detect gliadin-specific CD4+ T-cells in peripheral blood.

## Key findings

- Gliadin-specific T-cell frequencies were significantly higher in celiac patients compared to controls (p < 0.0001).
- A low-dose gluten challenge increased detectable T-cells in patients on a gluten-free diet.
- The test successfully aided in diagnosing challenging cases like seronegative celiac disease.

## Abstract

Discrepancy between serology and small bowel histology, such as seronegative CD, poses a diagnostic challenge in celiac disease (CD) diagnosis. Recently described methods to detect gliadin-specific T-cells are too laborious even in a specialized diagnostic setting. We developed a method, which can be implemented in specialized diagnostic laboratories.

Gliadin-specific T-cells were analyzed by α1-and α2-gliadin peptide loaded Dextramers (Dm) in healthy controls (HC, n = 18), patients with non-celiac gluten sensitivity (NCGS, n = 9), active CD (aCD, n = 7) and CD on a gluten free diet (GFD, n = 14). Control peptide (CLIP)-loaded Dm were used as background controls. The α-gliadin-Dm:CLIP-Dm ratio was calculated. In CD patients ≥5 years on GFD (n = 8), a randomized two-dose gluten challenge was performed to increase gliadin-specific T-cell frequencies.

Gliadin-specific CD4+ T-cell frequencies were significantly higher in aCD and GFD than in HC and NCGS (p ≤ 0.0001). In CD patients on a GFD ≥5 years, gliadin-specific T-cells were detectable in 6/8 patients after a week gluten challenge, and all tested positive within 4 weeks. Gliadin-specific T-cells significantly upregulated CD38 after 1 week of gluten ingestion (p < 0.008). Real world data from sixteen patients demonstrated the applicability of this test in diagnostic challenging cases.

Gliadin-specific T-cells can be detected in peripheral blood of CD patients using commercially available dextramers. These cells persist in CD patients on a GFD but may decline over time. A short term low-dose gluten challenge increased sensitivity. This simplified detection method of gliadin-specific T-cells is suitable for diagnostic challenging CD cases.

•Dextramers can detect peripheral blood gliadin-specific CD4+ T-cells with a straightforward flowcytometry analysis method.•Gliadin-specific T-cell frequency was significantly higher in CD patients compared to controls (p < 0.0001).•A low-dose gluten challenge can increase gliadin-specific T-cells to detectable levels when undetectable pre-challenge.•Gliadin-specific T-cell detection can aid in diagnosis of challenging clinical cases such as seronegative CD.

Dextramers can detect peripheral blood gliadin-specific CD4+ T-cells with a straightforward flowcytometry analysis method.

Gliadin-specific T-cell frequency was significantly higher in CD patients compared to controls (p < 0.0001).

A low-dose gluten challenge can increase gliadin-specific T-cells to detectable levels when undetectable pre-challenge.

Gliadin-specific T-cell detection can aid in diagnosis of challenging clinical cases such as seronegative CD.