Biological and clinical significance of T helper 17 cell deficiency: insight into monogenic defects.

Summary: T helper 17 (Th17) are a CD4+ T subpopulation cells which are involved in the host protection against microbes such as extracellular and intracellular bacteria, parasites, fungi, and viruses. Monogenic defects including those mutations in some genes such as the signal transducer and activator of transcription (STAT)1 and 3, dedicator of cytokinesis 8 (DOCK8), autoimmune regulator (AIRE), and interleukin 17 receptor A (IL-17RA) can lead to impairment in Th17 cell development and function along with the concomitant increased risk for chronic mucocutaneous candidiasis (CMC). The immunologic abnormalities in these patients include low frequency of Th17 cells; defective cutaneous or in vitro T cell response to Candida species, and/or autoantibodies against relevant cytokines. This review outlines the biological characteristics and functionality of Th17 cells, as well as the clinical features of individuals with genetic defects associated with Th17 deficiency.

The profile of IL-4, IL-5, IL-10 and GATA3 in patients with LRBA deficiency and CVID with no known monogenic disease: Association with disease severity.

BACKGROUND: Common variable immunodeficiency (CVID) is the most common symptomatic form of primary immunodeficiency (PID). LPS-responsive beige-like anchor protein (LRBA) deficiency is an autosomal recessive disease characterized by a CVID-like phenotype. T cell abnormality was reported in patients with CVID and LRBA deficiency. The study's aim was to evaluate IL-4, IL-5, IL-10 and GATA3 expression in patients with LRBA deficiency and CVID with no known monogenic disease, and further evaluate its relevance with immunological futures and clinical complications of patients. METHODS: The study population comprised patients with CVID, LRBA deficiency and age-sex matched healthy controls. Mutation analysis was done by whole exome sequencing in CVID patients to rule out monogenic PIDs. After CD4+ T cell stimulation with anti-CD3 and anti-CD28 monoclonal antibodies, gene expression of IL-4, IL-5, IL-10 and transcription factor GATA3 was evaluated by real-time polymerase chain reaction. The protein of mentioned cytokines was assessed by enzyme-linked immunosorbent assay. RESULTS: The main clinical presentations of CVID patients were infections only and lymphoproliferations phenotypes, but in LRBA patients were autoimmune and enteropathy phenotype. The frequencies of CD4+ T cells were significantly reduced in LRBA and CVID patients. There were no statistically significant differences among GATA3, IL4, and IL5 gene expressions by CD4+ T cells of patients and controls, however, the IL10 expressions in CVID patients was significantly lower than in LRBA patients and HCs. As compared with HCs, CVID patients showed a prominent decrease in IL-4 and IL-10 production by CD4+ T cells. CONCLUSIONS: Our findings demonstrated that patients with CVID and LRBA deficiency (even with severe infectious and inflammatory complications) have not imbalance in Th2 response, which is in parallel with lower frequency of allergy and asthma in these patients.