Cd4(+) T Cell-Released Extracellular Vesicles Potentiate the Efficacy of the Hbsag Vaccine by Enhancing B Cell Responses

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作者：Lu, J., Wu, J., Xie, F., Tian, J., Tang, X., Guo, H., Ma, J., Xu, P., Mao, L., Xu, H. & Wang, S.
期刊：Advanced science (Weinheim, Baden-Wurttemberg, Germany) 6, 1802219 (2019)
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T cells secrete bioactive extracellular vesicles (EVs), but the potential biological effects of CD4(+) T cell EVs are not clear. The main purpose of this study is to investigate the effects of CD4(+) T cell-derived EVs on B cell responses and examine their role in antigen-mediated humoral immune responses. In this study, CD4(+) T cell EVs are purified from activated CD4(+) T cells in vitro. After immunization with the Hepatitis B surface antigen (HBsAg) vaccine, CD4(+) T cell EVs-treated mice show stronger humoral immune responses, which is indicated by a greater Hepatitis B surface antibody (HBsAb) level in serum and a greater proportion of plasma cells in bone marrow. In addition, it is found that EVs released from activated CD4(+) T cells play an important role in B cell responses in vitro, which significantly promote B cell activation, proliferation, and antibody production. Interestingly, antigen-specific CD4(+) T cell EVs are found to be more efficient than control EVs in enhancing B cell responses. Furthermore, it is shown that CD40 ligand (CD40L) is involved in CD4(+) T cell EVs-mediated B cell responses. Overall, the results have demonstrated that CD4(+) T cell EVs enhance B cell responses and serve as a novel immunomodulator to promote antigen-specific humoral immune responses.