Hou, Tie ZhengVerma, NishaWanders, JenniferKennedy, AlanSoskic, BlagojeJanman, DanielHalliday, NeilRowshanravan, BehzadWorth, AustenQasim, WaseemBaxendale, HelenStauss, HansSeneviratne, SuranjithNeth, OlafOlbrich, PeterHambleton, SophieArkwright, Peter DBurns, Siobhan OWalker, Lucy S KSansom, David M2023-01-252023-01-252017-02-03Hou TZ, Verma N, Wanders J, Kennedy A, Soskic B, Janman D. et al. Identifying functional defects in patients with immune dysregulation due to LRBA and CTLA-4 mutations. Blood. 2017 Mar 16;129(11):1458-1468.http://hdl.handle.net/10668/10837Heterozygous CTLA-4 deficiency has been reported as a monogenic cause of common variable immune deficiency with features of immune dysregulation. Direct mutation in CTLA-4 leads to defective regulatory T-cell (Treg) function associated with impaired ability to control levels of the CTLA-4 ligands, CD80 and CD86. However, additional mutations affecting the CTLA-4 pathway, such as those recently reported for LRBA, indirectly affect CTLA-4 expression, resulting in clinically similar disorders. Robust phenotyping approaches sensitive to defects in the CTLA-4 pathway are therefore required to inform understanding of such immune dysregulation syndromes. Here, we describe assays capable of distinguishing a variety of defects in the CTLA-4 pathway. Assessing total CTLA-4 expression levels was found to be optimal when restricting analysis to the CD45RA-Foxp3+ fraction. CTLA-4 induction following stimulation, and the use of lysosomal-blocking compounds, distinguished CTLA-4 from LRBA mutations. Short-term T-cell stimulation improved the capacity for discriminating the Foxp3+ Treg compartment, clearly revealing Treg expansions in these disorders. Finally, we developed a functionally orientated assay to measure ligand uptake by CTLA-4, which is sensitive to ligand-binding or -trafficking mutations, that would otherwise be difficult to detect and that is appropriate for testing novel mutations in CTLA-4 pathway genes. These approaches are likely to be of value in interpreting the functional significance of mutations in the CTLA-4 pathway identified by gene-sequencing approaches.enCTLA-4 AntigenImmunotherapyImmunobiologyMutationLysosomesAdaptor Proteins, Signal TransducingCTLA-4 AntigenCell LineCommon Variable ImmunodeficiencyForkhead Transcription FactorsHumansImmune System PhenomenaLigandsMutationT-Lymphocytes, Regulatoryresearch article28159733Restricted AccessMutaciónLigandosGenesInmunodeficiencia variable comúnAptitudLinfocitos TSíndromeLinfocitos T reguladoresAfecto10.1182/blood-2016-10-7451741528-0020PMC5438243https://ashpublications.org/blood/article-pdf/129/11/1458/1398617/blood745174.pdfhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC5438243/pdf