Watson D L
Aust J Biol Sci. 1980 Aug;33(4):403-22. doi: 10.1071/bi9800403.
The mammary gland performs vitally important immunological roles, both in providing passive immune protection to the suckling infant and in immunological defence of its own tissues against infection with microorganisms. These immunological functions differ greatly between species of mammals in both nature and magnitude. In ungulates the mammary gland is singularly responsible for transfer of immunoglobulin (IgG) from mother to young. This process is dependent on a highly selective mechanism which results in the transport of blood-borne IgG molecules across secretory epithelial cells of the colostrum-forming mammary gland and into secretion. Upon ingestion of colostrum by the young ungulate this immunoglobulin is absorbed across the wall of the small intestine and thence into the bloodstream. In other species, including rodents and primates, there is a well-developed local IgA system operating in the mammary gland. In this situation, plasma cells located near the basal membranes of secretory epithelial cells secrete IgA which passes through the epithelial cells and into colostrum of milk. In the species the IgA in mammary secretions is not absorbed into the circulation of the suckling infant; because of its unique property of resisting proteolytic degradation, it may mediate a local protective role in the lumen of the intestine of the suckling infant. Specific immunological protection of mammary tissue may be mediated through blood-derived antibody (particularly IgG), locally synthesized antibody (particularly IgA) or phagocytic cells. Neutrophils arrive in mammary tissue and secretions in very large numbers following bacterial invasion of the gland. It has been established recently that these cells carry cytophilic antibody on their cell membrane. This cytophilic antibody can play an important functional role in enhancing the phagocytic capacity of neutrophils in the mammary gland.
乳腺发挥着至关重要的免疫作用，既为哺乳婴儿提供被动免疫保护，也对自身组织进行免疫防御以抵抗微生物感染。这些免疫功能在哺乳动物的不同物种之间，无论是性质还是程度上都有很大差异。在有蹄类动物中，乳腺单独负责将免疫球蛋白（IgG）从母体传递给幼崽。这个过程依赖于一种高度选择性的机制，该机制导致血源性IgG分子穿过形成初乳的乳腺分泌上皮细胞并进入分泌物中。幼龄有蹄类动物摄入初乳后，这种免疫球蛋白会从小肠壁吸收，然后进入血液循环。在其他物种，包括啮齿动物和灵长类动物中，乳腺中存在一个发育良好的局部IgA系统。在这种情况下，位于分泌上皮细胞基底膜附近的浆细胞分泌IgA，IgA穿过上皮细胞进入乳汁或初乳中。在这些物种中，乳腺分泌物中的IgA不会被吸收到哺乳婴儿的循环系统中；由于其具有抵抗蛋白水解降解的独特特性，它可能在哺乳婴儿肠道腔内发挥局部保护作用。乳腺组织的特异性免疫保护可能通过血液来源的抗体（特别是IgG）、局部合成的抗体（特别是IgA）或吞噬细胞来介导。细菌侵入乳腺后，中性粒细胞会大量到达乳腺组织和分泌物中。最近已经确定，这些细胞在其细胞膜上携带嗜细胞抗体。这种嗜细胞抗体在增强乳腺中中性粒细胞的吞噬能力方面可以发挥重要的功能作用。
