信号素(Sema)家族最初被定义为轴突导向因子，在神经系统的轴突导向中发挥重要作用。随后越来越多的研究结果证明，Sema家族亦参与免疫应答、肿瘤血管生成和器官形成等过程。Sema3A是Sema家族中最早被研究的轴突导向因子。近年研究发现，Sema3A在肿瘤及自身免疫性疾病(AD)的发生、发展过程中，发挥重要的作用。然而，Sema3A在肿瘤的发生、发展过程中，是发挥抑制作用还是促进作用，目前的研究观点尚不一致。阐明Sema3A在肿瘤和自身免疫调节中的作用，有望为以Sema3A为靶点的免疫治疗，提供新的思路。因此，笔者拟就Sema3A的结构及受体，以及Sema3A在肿瘤及AD中的作用和机制的最新研究进展进行综述。“,”Semaphorin (Sema) family is originally defined as axonal guidance factors, which plays an important role in axon-directing of the nervous system. Subsequently, increasing studies have shown that Sema family is also involved in immune response, tumor angiogenesis and organogenesis. Sema3A is the earliest studied axonal guidance factor in the Sema family. In recent years, it has been found that Sema3A has also played an important role in the occurrence and development of tumors and autoimmune diseases (AD). However, whether Sema3A plays an inhibitory or facilitative role in tumorigenesis is still inconsistent. To elucidate the role of Sema3A in tumor immunity and autoimmune regulation is expected to provide new ideas for immunotherapy targeting Sema3A. Therefore, this article reviews the latest research progress on the structure and receptors of Sema3A, as well as role and mechanisms of Sema3A in neoplasms and AD.