Congenital T-cell activation impairs transitional-to-follicular B-cell maturation in humans

Abstract: Patients with cytotoxic T-lymphocyte–associated protein 4 (CTLA4) deficiency exhibit profound humoral immune dysfunction, yet the basis for the B-cell defect is not known. We observed a marked reduction in transitional-to-follicular (FO) B-cell development in patients with CTLA4 deficiency...

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Main Authors: Hugues Allard-Chamard, Kirsty Hillier, Michelle L. Ramseier, Alice Bertocchi, Naoki Kaneko, Katherine Premo, Grace Yuen, Marshall Karpel, Vinay S. Mahajan, Christina Tsekeri, Joseph S. Hong, Jean Vencic, Rory Crotty, Anish V. Sharda, Sara Barmettler, Emma Westermann-Clark, Jolan E. Walter, Musie Ghebremichael, Alex K. Shalek, Jocelyn R. Farmer, Shiv Pillai
Format: Article
Language:English
Published: Elsevier 2025-02-01
Series:Blood Advances
Online Access:http://www.sciencedirect.com/science/article/pii/S2473952924006918
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Summary:Abstract: Patients with cytotoxic T-lymphocyte–associated protein 4 (CTLA4) deficiency exhibit profound humoral immune dysfunction, yet the basis for the B-cell defect is not known. We observed a marked reduction in transitional-to-follicular (FO) B-cell development in patients with CTLA4 deficiency, correlating with decreased CTLA4 function in regulatory T cells, increased CD40L levels in effector CD4+ T cells, and increased mammalian target of rapamycin complex 1 (mTORC1) signaling in transitional B cells (TrBs). Treatment of TrBs with CD40L was sufficient to induce mTORC1 signaling and inhibit FO B-cell maturation in vitro. Frequent cell-to-cell contacts between CD40L+ T cells and immunoglobulin D–positive CD27– B cells were observed in patient lymph nodes. FO B-cell maturation in patients with CTLA4 deficiency was partially rescued after CTLA4 replacement therapy in vivo. We conclude that functional regulatory T cells and the containment of excessive T-cell activation may be required for human TrBs to mature and attain metabolic quiescence at the FO B-cell stage.
ISSN:2473-9529