Bassagh A, et al. - In the present study, researchers examined interleukin-35 (IL-35) levels and a single nucleotide polymorphism, rs3761548, in FOXP3 gene in Helicobacter pylori-infected patients with peptic ulcer (PU), to clarify possible connections via analyzing data of 100 H. pylori-infected PU patients, 100 H. pylori-infected asymptomatic subjects (AS), and 100 noninfected healthy subjects (NHSs). Using ELISA and RFLP-PCR methods, serum IL-35 levels and the genotyping were determined, respectively. Results of this study suggested that decreased IL-35 levels could be involved in PU development in H. pylori-infected individuals. Data reported that IL-35 levels were affected by CagA status of H. pylori, participants gender, and genetic variations at rs3761548. Risk factor for PU development could be AA genotype and A allele at rs3761548.