Brown W R, Isobe K, Nakane P K, Pacini B
Gastroenterology. 1977 Dec;73(6):1333-9.
We conducted studies concerning the issue of whether secretory component (SC) is a specific receptor on intestinal epithelial cells for IgA and IgM. Initially, frozen sections of human intestinal mucosa were incubated with dimeric monoclonal human IgA, conjugated to horseradish peroxidase; adjacent sections were reacted with peroxidase-conjugated antibodies to SC. The conjugated IgA and anti-SC bound to similar sites in the epithelium, that is to basolateral margins and supranuclear cytoplasm of columnar epithelial cells, principally in gland crypts. In subsequent tests of binding specificity, binding of the dimeric IgA conjugate was inhibited by pretreating the tissues with unconjugated dimeric IgA or 19S IgM, pretreating the tissues with unconjugated antibodies to SC, or preincubating the dimeric IgA conjugate with free SC. Binding was not inhibited or only partially inhibited by pretreating the tissues with monomeric IgA or IgG, pretreating the tissues with antibodies to human or heterologous immunoglobulins, or preincubating the dimeric IgA conjugate with 11S secretory colostral IgA. The findings indicate that dimeric IgA and 19S IgM are capable of binding in vitro to specific sites on intestinal epithelial cells, most likely to SC. This supports the hypothesis that transport of these immunoglobulins into intestinal fluids involves their combination with SC in the epithelium.
我们开展了有关分泌成分（SC）是否为肠道上皮细胞上IgA和IgM特异性受体这一问题的研究。最初，将人肠道黏膜冰冻切片与偶联辣根过氧化物酶的二聚体人单克隆IgA一起孵育；相邻切片与抗SC的过氧化物酶偶联抗体反应。偶联的IgA和抗SC在上皮细胞的相似部位结合，即主要在腺隐窝的柱状上皮细胞的基底外侧边缘和核上细胞质。在随后的结合特异性测试中，通过用未偶联的二聚体IgA或19S IgM预处理组织、用未偶联的抗SC抗体预处理组织或使二聚体IgA偶联物与游离SC预孵育，二聚体IgA偶联物的结合受到抑制。用单体IgA或IgG预处理组织、用抗人或异源免疫球蛋白的抗体预处理组织或使二聚体IgA偶联物与11S分泌型初乳IgA预孵育，结合未受抑制或仅部分受抑制。这些发现表明，二聚体IgA和19S IgM在体外能够与肠道上皮细胞上的特定位点结合，最有可能是与SC结合。这支持了以下假说：这些免疫球蛋白转运到肠液中涉及它们与上皮细胞中的SC结合。
