Abstract: Su Huichun, Luo Yang, Liu Xiaochun, Han Yue, Wen He, Yao Xu, Wang Baoxi Department of Allergy and Rheumatology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing 210042, China （Su HC［current affiliation: Department of Dermatology, The First Affiliated Hospital of Fujian Medical University, Fuzhou 350004, China］, Luo Y, Han Y, Liu XC, Wen H, Yao X）; Department of Dermatology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100144, China （Wang BX） Corresponding authors: Yao Xu, Email: dryao_xu@126.com; Wang Baoxi, Email: wangbx@ncstdlc.org 【Abstract】 Objective To evaluate the recognition and uptake of transglutaminase 3 （TG3） by dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin （DC-SIGN） receptors on the membrane surface of DC-SIGN-transfected human embryonic kidney （HEK） 293T cells and monocyte-derived dendritic cells （MDDCs）. Methods The eukaryotic vector pGCMV-enhanced green fluorescent protein （EGFP） containing DC-SIGN gene fragments was transfected into HEK293T cells to prepare DC-SIGN-EGFP-HEK293T cells by using liposome transfection method. CD14+ monocytes were isolated from peripheral blood samples by magnetic bead-based negative selection, and then were induced by granulocyte-macrophage colony stimulating factor （GM-CSF） and interleukin-4 （IL-4） to prepare MDDCs. Laser confocal microscopy and flow cytometry were performed to evaluate the recognition and uptake of TG3 protein by DC-SIGN receptors on the surface of HEK293T cells and MDDCs. MDDCs treated without Alexa Fluor 647 dye-tagged TG3 served as blank control group, and those treated with Alexa Fluor 647 dye alone served as negative control group. Results After co-culture with TG3 for 3 hours, laser confocal microscopy and flow cytometry both showed that TG3 could be recognized by and uptaken through DC-SIGN receptors into HEK293T cells and MDDCs. Flow cytometry also revealed that the binding of TG3 to MDDCs could be partially blocked by DC-SIGN blocking antibodies. Neither the negative control group nor the blank control group showed the recognition and binding of TG3 to HEK293T cells and MDDCs. Conclusion TG3 can serve as a kind of autoantigen to be recognized and bound by DC-SIGN receptors, followed by uptake by dendritic cells.