RT Journal Article SR Electronic T1 Human MAIT cells are devoid of alloreactive potential: prompting their use as universal cells for adoptive immune therapy JF Journal for ImmunoTherapy of Cancer JO J Immunother Cancer FD BMJ Publishing Group Ltd SP e003123 DO 10.1136/jitc-2021-003123 VO 9 IS 10 A1 Marie Tourret A1 Nana Talvard-Balland A1 Marion Lambert A1 Ghada Ben Youssef A1 Mathieu F Chevalier A1 Armelle Bohineust A1 Thomas Yvorra A1 Florence Morin A1 Saba Azarnoush A1 Olivier Lantz A1 Jean-Hugues Dalle A1 Sophie Caillat-Zucman YR 2021 UL http://jitc.bmj.com/content/9/10/e003123.abstract AB Background Mucosal-associated invariant T (MAIT) cells are semi-invariant T cells that recognize microbial antigens presented by the highly conserved MR1 molecule. MAIT cells are predominantly localized in the liver and barrier tissues and are potent effectors of antimicrobial defense. MAIT cells are very few at birth and accumulate gradually over a period of about 6 years during the infancy. The cytotoxic potential of MAIT cells, as well as their newly described regulatory and tissue repair functions, open the possibility of exploiting their properties in adoptive therapy. A prerequisite for their use as ‘universal’ cells would be a lack of alloreactive potential, which remains to be demonstrated.Methods We used ex vivo, in vitro and in vivo models to determine if human MAIT cells contribute to allogeneic responses.Results We show that recovery of MAIT cells after allogeneic hematopoietic stem cell transplantation recapitulates their slow physiological expansion in early childhood, independent of recovery of non-MAIT T cells. In vitro, signals provided by allogeneic cells and cytokines do not induce sustained MAIT cell proliferation. In vivo, human MAIT cells do not expand nor accumulate in tissues in a model of T-cell-mediated xenogeneic graft-versus-host disease in immunodeficient mice.Conclusions Altogether, these results provide evidence that MAIT cells are devoid of alloreactive potential and pave the way for harnessing their translational potential in universal adoptive therapy overcoming barriers of HLA disparity.Trial registration number ClinicalTrials.gov number NCT02403089.Data are available on reasonable request. Data are available upon reasonable request to sophie.caillat-zucman@aphp.fr.