P215 Deep immune phenotyping of unconventional T cells reveals a depletion in Mucosa Associated T Cells (MAIT) in IBD patients with extraintestinal manifestations

Catalàn-Serrax, I.(1,2,3)*;Xu, W.(4);Bruland, T.(5);Larbi, A.(6);Sandvik, A.K.(5,7,8);

(1)Levanger Hospital- Nord-Trondelag Hospital Trust., Department of Gastroenterology, Levanger, Norway;(2)Centre of Molecular Inflammation Research- NTNU-Norwegian University of Science and Technology, Cemir, Trondheim, Norway;(3)Norwegian University of Science and Technology NTNU, Department of Clinical and Molecular Medicine IKOM, Trondheim, Norway;(4)Agency for Science Technology and Research, Singapore Immunology Network SIgN, Singapore, Singapore;(5)Norwegian University of Science and Technology, Department of Clinical and Molecular Medicine IKOM, Trondheim, Norway;(6)Agency for Science Technology and Research, Agency for Science Technology and Research, Singapore, Singapore;(7)Centre of Molecular Inflammation Research, Cemir, Trondheim, Norway;(8)St. Olav’s University Hospital, Department of Gastroenterology and Hepatology- Clinic of Medicine, Trondheim, Norway;


Extraintestinal manifestations (EIM) are common in IBD and they affect importantly the quality of life of patients. Although the pathogenesis of EIM is still poorly understood, an altered immune response involving T cells has been proposed. In addition, the presence of EIM during disease course will impact the therapeutic choices with new biologics.

In the present work we aim to characterize T cell populations -with focus on Uncoventional T cells- in IBD patients presenting EIM using advance flow cytometry and proteomics.


A total of 184 individuals (106 F/78 M) and were prospectively included: 149 IBD patients (84 UC/65 CD) and 25 healthy matched controls. Biologic samples including Peripheral Blood Mononuclear Cells (PBMC) and plasma were consecutively stored and classified in an established cross sectional IBD biobank at the Norwegian University of Science and Technology. Patient characteristics including age, sex, smoking status, current medication, Montreal Classification phenotype and inflammation biomarkers (CRP) and fecal Calprotectin were recorded.

PBMC were stained with antibodies and acquired using BD FACS Symphony flow cytometer using automatic compensations and Multiplex ELISA for 65 proteins was performed using Immune Monitoring 65-Plex Human ProcartaPlex™ Panel at Singapore Immunology Network (SIgN), as previously described.

Statistical analysis was performed using GraphPad Prism (San Diego, CA). p≤ 0.05 was considered statistically significant.


Of the 184 IBD patients included, the presence or not of EIM was registered in 149 (mean age 37 +/-7.2; 86 female) of which 84 had UC and 65 CD. Of them, 21 (14.1%) presented EIM at inclusion. We analyzed the differences in all subsets of unconventional T cells: gammadelta T cells (VD1, VD2, VD3), MAIT cells, innate NKT cells and CD4/CD8 positive T cells between IBD patients with or without EIM (Fig1A). MAIT cells were selectively depleted in patients with EIM (p<0.01), while there was no statistically significant change in the ratios of other T cell subpopulations.

We then studied the concentrations of plasma proteins between the two groups. We found a significant increase in IL-2, GM-CSF, IL-6, Eotaxin, Leukemia Inhibitory Factor Protein (LIF), TNF-RII and Monocyte Chemoattractant Protein-1 (MCP), all p<0.05 in patients with EIM (Fig1B).

In order to address the potential use of MAIT as marker of EIM we constructed a ROC curve showing an AUC 0.752 (95% CI 0.639-0.865, p= 0.0002) Fig. 1Cfigure 1


MAIT cell depletion associated strongly with the presence of EIM and could be used as a clinical marker for EIM in IBD. A deeper understanding of its role in the pathogenesis of EIM, as well as an external validation as a marker, deserves further investigation.