Salmon H
Laboratoire Lymphocytes et Immunité des Muqueuses, INRA, Nouzilly.
Adv Exp Med Biol. 2000;480:279-86. doi: 10.1007/0-306-46832-8_32.
Since placenta of pregnant sows are impermeable to immunoglobulin passage, the neonates are born agammaglobulinemic; although immunocompetent, they are unable to develop rapidly an immune response which will protect their systemic and mucosal compartments; thus their survival depend upon the passive acquisition of maternal immunity including at least 3 components: i) a systemic humoral immunity, transmitted through colostrum conveying mainly by IgG; these IgG are transferred from maternal serum via Fc gamma receptors on the epithelial cells of mammary gland (MG). ii) a local humoral immunity, especially secretory IgA (IgAs), transmitted mainly by milk (lactogenic immunity) until weaning. IgAs are secreted by MG recruited plasma cells and are excreted in milk via secretory component of epithelial cells: these IgA exhibit a specificity for the antigens present in the maternal digestive tract, the so-called "entero-mammary link"; this link is due to the migration of lymphocytes from the gut to the mammary gland; they are recruited from the blood via the interaction of their homing receptor (alpha 4 beta 7) with the developmentally regulated mucosal vascular addresin MadCAM-1. In the MG, MadCAM-1 increased in pregnancy (probably under oestrogenic stimulation) but regressed in lactation; its density is closely related to the T cell numbers in MG; in contrast the increase in plasma cell numbers is not related to MadCAM-1 density. Thus IgA precursor cells (alpha 4 beta 7 B cells) seem to be recruited by a milk B cell chemoattractant. On the other hand, presence of T and B lymphocytes in MG (some of them originating from the systemic compartment), sustains the attempts of MG immunization and the results sustain the view of a true local immune response. iii) possibly but not formally proved, a cellular immunity transmitted via maternal immunocompetent cells present in mammary secretions; the exported lymphocytes may represent a selected population of lymphocytes after their passage through the MG epithelium.
由于怀孕母猪的胎盘对免疫球蛋白的通过具有屏障作用，新生仔猪出生时无丙种球蛋白血症；尽管它们具有免疫能力，但无法迅速产生能保护其全身和黏膜腔室的免疫反应；因此，它们的存活依赖于被动获得母体免疫，这至少包括三个成分：i）一种全身体液免疫，通过初乳传递，主要由IgG介导；这些IgG通过乳腺上皮细胞（MG）上的Fcγ受体从母体血清转移而来。ii）一种局部体液免疫，特别是分泌型IgA（IgAs），主要通过乳汁传递（生乳免疫）直至断奶。IgAs由MG募集的浆细胞分泌，并通过上皮细胞的分泌成分排泄到乳汁中：这些IgA对母体消化道中存在的抗原具有特异性，即所谓的“肠-乳腺联系”；这种联系是由于淋巴细胞从肠道迁移到乳腺；它们通过归巢受体（α4β7）与发育调控的黏膜血管地址素MadCAM-1的相互作用从血液中募集而来。在MG中，MadCAM-1在怀孕期间增加（可能受雌激素刺激），但在哺乳期退化；其密度与MG中的T细胞数量密切相关；相比之下，浆细胞数量的增加与MadCAM-1密度无关。因此，IgA前体细胞（α4β7 B细胞）似乎是由一种乳汁B细胞趋化因子募集的。另一方面，MG中存在T和B淋巴细胞（其中一些来自全身腔室），维持了MG免疫的尝试，并且结果支持了存在真正局部免疫反应的观点。iii）可能但尚未正式证实，一种通过乳腺分泌物中存在的母体免疫活性细胞传递的细胞免疫；输出的淋巴细胞可能代表它们通过MG上皮后经过选择的淋巴细胞群体。
