Single cell profiling of peanut-responsive T cells in peanut allergic subjects reveals heterogeneous effector Th2 subsets

Publication date: Available online 31 January 2018
Source:Journal of Allergy and Clinical Immunology
Author(s): David Chiang, Xintong Chen, Stacie M. Jones, Robert A. Wood, Scott H. Sicherer, A. Wesley Burks, Donald Y.M. Leung, Charuta Agashe, Alexander Grishin, Peter Dawson, Wendy F. Davidson, Leah Newman, Robert Sebra, Miriam Merad, Hugh A. Sampson, Bojan Losic, M. Cecilia Berin
BackgroundThe contribution of phenotypic variation of peanut-specific T cells to clinical allergy or tolerance to peanut is not well understood.ObjectivesOur objective was to comprehensively phenotype peanut-specific T cells in the peripheral blood of individuals with and without peanut allergy (PA).MethodsWe obtained samples from PA individuals, including a cohort undergoing baseline peanut challenges for an immunotherapy trial (CoFAR6). Subjects were confirmed as PA, or if they passed a 1 g peanut challenge they were termed high-threshold (HT). Healthy controls (HC) were also recruited. Peanut-responsive T cells were identified by CD154 expression after 6-18h of stimulation with peanut extract. Cells were analyzed by flow cytometry and single cell RNA sequencing.ResultsPA individuals had tissue and follicle-homing peanut-responsive CD4+ T cells with a heterogeneous pattern of Th2 differentiation, while controls had undetectable T cell responses to peanut. The PA group had a delayed and IL-2-dependent upregulation of CD154 on cells expressing Treg markers, which was absent in HC or HT individuals. Depletion of Tregs in vitro enhanced cytokine production in HC and PA subjects, but cytokines associated with highly differentiated Th2 cells were more resistant to Treg suppression in PA subjects. Analysis of gene expression by single cell RNAseq identified T cells with highly correlated expression of IL4, IL5, IL9, IL13 and the IL-25 receptor IL17RB.ConclusionsThese results demonstrate the presence of highly differentiated Th2 cells producing Th2-associated cytokines with functions beyond IgE-class switch in peanut allergy. A multi-functional Th2 response was more evident than a Treg deficit among peanut-responsive T cells.

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