Objective:To investigate whether indoleamine 2, 3-dioxygenase-1 (IDO1) is involved in Neisseria gonorrhoeae ( Ng) infection and its immunomodulatory role in Ng infection. Methods:Human peripheral blood mononuclear cells were induced to differentiate into DC in vitro. The phenotype of DC was identified. The expression of IDO1 was detected by Western blot. The expression of IDO1 at mRNA level in the secretions of Ng-positive patients was detected. Changes in Treg and myeloid-derived suppressor cell (MDSC) in the anticoagulant whole blood of Ng-positive patients were detected by flow cytometry. Results:Ng could induce human DCs to produce IDO1, which depended on the activity of Ng. The expression of IDO1 in the genital tract secretions of Ng-positive patients was significantly higher than that in healthy people. Besides, the proportions of MDSC and Treg in the peripheral blood of patients with Ng infection were higher than those in healthy people. Based on literature review, it was suggested that Treg could induce the expression of IDO1 +, and IDO1 +, in turn, together with MDSC, promoted the differentiation of new Treg, which inhibited the proliferation of CD4 + T cells and was involved in immune tolerance. Conclusions:Understanding the immune regulatory network of "IDO1-CD4 + T cells-immune microenvironment" in the immune microenvironment would provide new targets or thoughts for the immunotherapy of gonorrhea, so as to better use immunotherapy to prevent and control the occurrence and development of gonorrhea.