IL18 and infection: The study goals included an analysis of serum interleukin (IL)-17A, IL-18, IL-23, regulated upon activation normal T-cell expressed and secreted (RANTES), and induced protein (IP)-10, as well as IgG4 concentrations in children admitted to the General Pediatric Ward for RRIs, and an assessment of the biomarkers tested as predictors of recurrent infections.