Carlos A Arango-Franco, Masato Ogishi, Susanne Unger, Ottavia M Delmonte, Julio César Orrego, Ahmad Yatim, Margarita M Velasquez-Lopera, Andrés F Zea-Vera, Jonathan Bohlen, Marwa Chbihi, Antoine Fayand, Juan Pablo Sánchez, Julian Rojas, Yoann Seeleuthner, Tom Le Voyer, Quentin Philippot, Kathryn J Payne, Adrian Gervais, Lucia V Erazo-Borrás, Luis A Correa-Londoño, Axel Cederholm, Alejandro Gallón-Duque, Pedro Goncalves, Jean-Marc Doisne, Liran Horev, Bénédicte Charmeteau-de Muylder, Jesús Á Álvarez, Diana M Arboleda, Lizet Pérez-Zapata, Estefanía Vásquez-Echeverri, Marcela Moncada-Vélez, Juan A López, Yolanda Caicedo, Boaz Palterer, Pablo J Patiño, Carlos J Montoya, Matthieu Chaldebas, Peng Zhang, Tina Nguyen, Cindy S Ma, Mohamed Jeljeli, Juan F Alzate, Felipe Cabarcas, Taushif Khan, Darawan Rinchai, Jean-Luc Prétet, Bertrand Boisson, Nico Marr, Ruba Ibrahim, Vered Molho-Pessach, Stéphanie Boisson-Dupuis, Dimitra Kiritsi, João T Barata, Nils Landegren, Bénédicte Neven, Laurent Abel, Andrea Lisco, Vivien Béziat, Emmanuelle Jouanguy, Jacinta Bustamante, James P Di Santo, Stuart G Tangye, Luigi D Notarangelo, Rémi Cheynier, Ken Natsuga, Andrés A Arias, José Luis Franco, Klaus Warnatz, Jean-Laurent Casanova, Anne Puel
The Journal of clinical investigation 134 (19) 2024/10/01
[Refereed] Infants with biallelic IL7R loss-of-function variants have severe combined immune deficiency (SCID) characterized by the absence of autologous T lymphocytes, but normal counts of circulating B and NK cells (T-B+NK+ SCID). We report 6 adults (aged 22 to 59 years) from 4 kindreds and 3 ancestries (Colombian, Israeli Arab, Japanese) carrying homozygous IL7 loss-of-function variants resulting in combined immunodeficiency (CID). Deep immunophenotyping revealed relatively normal counts and/or proportions of myeloid, B, NK, and innate lymphoid cells. By contrast, the patients had profound T cell lymphopenia, with low proportions of innate-like adaptive mucosal-associated invariant T and invariant NK T cells. They also had low blood counts of T cell receptor (TCR) excision circles, recent thymic emigrant T cells and naive CD4+ T cells, and low overall TCR repertoire diversity, collectively indicating impaired thymic output. The proportions of effector memory CD4+ and CD8+ T cells were high, indicating IL-7-independent homeostatic T cell proliferation in the periphery. Intriguingly, the proportions of other T cell subsets, including TCRγδ+ T cells and some TCRαβ+ T cell subsets (including Th1, Tfh, and Treg) were little affected. Peripheral CD4+ T cells displayed poor proliferation, but normal cytokine production upon stimulation with mitogens in vitro. Thus, inherited IL-7 deficiency impairs T cell development less severely and in a more subset-specific manner than IL-7R deficiency. These findings suggest that another IL-7R-binding cytokine, possibly thymic stromal lymphopoietin, governs an IL-7-independent pathway of human T cell development.