IDO1-mediated M2 macrophage polarization alleviates the progression of ankylosing spondylitis. Kangqi Ji Lingfei Wang Weijie Liu Genfeng Li Xiaoyu Lian Jun Fan Chen Song Yanpeng Jian a Department of Spine Surgery, Central Hospital of Xuchang City, Xuchang, Chinab Hematology Laboratory, The First Affiliated Hospital of Xinxiang Medical University, Xinxiang, China