Browse by author
Lookup NU author(s): Professor Sophie Hambleton
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2019, The Author(s). Background: Inducible T cell co-stimulator (ICOS) deficiency has been categorized as a combined immunodeficiency often complicated by enteropathies, autoimmunity, lymphoproliferation, and malignancy. We report seven new patients and four novel ICOS mutations resulting in a common variable immunodeficiency (CVID)–like phenotype and show that dysregulated IL-12 release, reduced cytotoxic T lymphocyte–associated protein 4 (CTLA4) expression, and skewing towards a Th1-dominant phenotype are all associated with inflammatory complications in this condition. Methods: A combination of whole exome and Sanger sequencing was used to identify novel mutations. Standard clinical and immunological evaluation was performed. FACS and ELISA-based assays were used to study cytokine responses and ICOS/ICOSL/CTLA4 expression following stimulation of whole blood and PBMCs with multiple TLR ligands, anti-CD3, and PHA. Results: Four novel ICOS mutations included homozygous c.323_332del, homozygous c.451C>G, and compound heterozygous c.58+1G>A/c.356T>C. The predominant clinical phenotype was that of antibody deficiency associated with inflammatory complications in 4/7 patients. Six out of seven patients were treated with immunoglobulin replacement and one patient died from salmonella sepsis. All patients who were tested showed reduced IL-10 and IL-17 cytokine responses, normal IL-1β, IL6, and TNF release following LPS stimulation and highly elevated IL-12 production in response to combined LPS/IFNγ stimulation. This was associated with skewing of CD4+ T cells towards Th1 phenotype and increased expression of ICOSL on monocytes. Lastly, reduced CTLA4 expression was found in 2 patients. One patient treated with ustekinumab for pancytopenia due to granulomatous bone marrow infiltration failed to respond to this targeted therapy. Conclusions: ICOS deficiency is associated with defective T cell activation, with simultaneously enhanced stimulation of monocytes. The latter is likely to result from a lack of ICOS/ICOSL interaction which might be necessary to provide negative feedback which limits monocytes activation.
Author(s): Abolhassani H, El-Sherbiny YM, Arumugakani G, Carter C, Richards S, Lawless D, Wood P, Buckland M, Heydarzadeh M, Aghamohammadi A, Hambleton S, Hammarstrom L, Burns SO, Doffinger R, Savic S
Publication type: Article
Publication status: Published
Journal: Journal of Clinical Immunology
Year: 2020
Volume: 40
Pages: 277-288
Print publication date: 01/02/2020
Online publication date: 20/12/2019
Acceptance date: 13/12/2019
Date deposited: 10/01/2020
ISSN (print): 0271-9142
ISSN (electronic): 1573-2592
Publisher: Springer Nature
URL: https://doi.org/10.1007/s10875-019-00735-z
DOI: 10.1007/s10875-019-00735-z
Altmetrics provided by Altmetric
