IL-17 Producing T cells as Predictors of Primary Immunodeficiencies in Patients with Candida Infections

Background: IL-17 producing T cells are a distinct subset of CD4+ T cells, which are recognized to have an essential role in protection against certain fungi and extracellular pathogens. Objectives: This study aims to evaluate the number of IL-17 producing T cells as a predictor of primary immunodeficiency disorders in patients with Candida infections and low numbers of IL-17 producing T cells. Methods: Seven newly diagnosed patients with documented Candida infections aged between 4 and 35 years were included in this study. Before establishing the diagnosis of chronic mucocutaneous candidiasis, a thorough immunodeficiency workup, including complete blood count, serum Ig levels and antibody responses, flow-cytometry evaluation, and LTT, was completed for all the patients, and other immunodeficiency disorders, including combined and phagocytic deficiencies, were ruled out. Then, IL-17 producing T cells were detected using antiCD3 and anti-IL-17 antibodies through flow-cytometry evaluation. Results: The IL-17 producing T cells significantly decreased in the peripheral blood of patients with PID and candida infections. A P-value of less than 0.05 was considered statistically significant. Conclusions: To conclude, in cases of recurrent candida infections, initial assessment of IL-17 producing T cells may act as a predictor of an underlying primary immunodeficiency. In patients with low counts of IL-17 producing T cells, selecting a targeted panel of genetic tests may become more helpful in the detection of certain immunodeficiency disorders than performing whole-exome sequence analysis.