防御素（defensin）是一类富含半胱氨酸的内源性抗微生物小分子多肽，人防御素可分成α-、β-和θ-防御素3种。除广谱抗微生物活性外，防御素还具有免疫调节、调理吞噬、细胞毒性等多种生物活性，在抗感染和杀伤肿瘤细胞等方面具有强大的作用。细胞毒性、免疫活性、抑制肿瘤新生血管的形成是防御素抗肿瘤的主要机制。本文就防御素的结构特点、生物活性、抗肿瘤作用及其机制作一详细综述。

Defensins are small endogenous antimicrobial peptides rich in cysteines. Human defensins can be divided into α-, β- and θ-defensins. In addition to broad-spectrum antimicrobial activities, Defensins also have anti-virus, immunomodulatory, opsonophagocytosis, cytotoxicity and other biological activities; and they play important roles in anti-infection and anti-tumor effects. Cytotoxicity, immune mechanism and anti-angiogenesis of tumors are the main mechanisms of the anti-tumor effects of defensins. In this paper we review the structural features, biological activities, anti-tumor effects/mechanism of defensin.