Loss of Circulating Mucosal-Associated Invariant T Cells in Common Variable Immunodeficiency Is Associated with Immune Activation and Loss of Eomes and PLZF

Abstract

Abstract Common variable immunodeficiency (CVID) is characterized by low levels of Igs leading to increased risk of infections. Mucosal-associated invariant T (MAIT) cells are a recently identified population of innate T cells with potent antibacterial activity. We hypothesized that CVID is associated with alterations in MAIT cells. Cryopreserved PBMC from CVID patients and healthy controls were used to study the frequency, phenotype, and response to Escherichia coli stimulation of MAIT cells by flow cytometry. MAIT cell frequency and absolute counts were depressed in CVID. Residual MAIT presented elevated coexpression of CD38 and HLA-DR, and reduced expression of CCR6, whereas levels of CD127 (IL-7 receptor) were unchanged. CVID patients also had an accumulation of MAIT cells lacking the critical transcription factors eomesodermin and promyelocytic leukemia zinc finger protein. MAIT cell frequency was inversely associated with levels of soluble CD14, with coexpression of CD38 and HLA-DR, and accumulation of MAIT cells lacking eomesodermin or promyelocytic leukemia zinc finger protein expression. None of these changes were normalized by IgG replacement therapy. Finally, MAIT cells from CVID patients displayed poor IFN-γ responses to E. coli stimulation, in part due to defective Ag presentation, and these responses were increased by pretreatment with IL-7. Defective MAIT cell response may contribute to the increased incidence of microbial infections seen in CVID patients on IgG replacement therapy.