Gregory R L
Department of Oral Biology, Indiana University, Indianapolis, Indiana 46202-5186, USA.
Clin Diagn Lab Immunol. 2001 May;8(3):540-4. doi: 10.1128/CDLI.8.3.540-544.2001.
Streptococcus mutans is present in the saliva of most individuals and is modified by salivary components bound to the cells. These saliva-bound S. mutans are swallowed, exposed to high levels of acidity in the stomach, and presented to the common mucosal immune system. Much effort has been directed to identifying the specific S. mutans antigens that the mucosal immune responses are directed against. However, little is known about the host-altered antigenic determinants that the mucosal immune system recognizes. The immunogenicity of gastrically intubated untreated S. mutans cells, cells coated with whole human saliva, cells treated with HCl (pH 2.0), and saliva-coated and acid-treated cells in mice was investigated. Saliva and serum samples were assayed by enzyme linked immunosorbent assay for immunoglobulin A (IgA) and IgG antibodies, respectively, against the untreated or treated S. mutans cells. In general, the levels of salivary IgA and serum IgG antibodies to the antigen against which the mice were immunized were significantly higher (P < or = 0.05). In addition, human saliva and serum samples from 12 subjects were assayed for naturally occurring antibody against the untreated or treated S. mutans cells. In every case, significantly higher reactivity was directed against the saliva-coated and acid-treated cells followed by the saliva-coated S. mutans. These results provide evidence for the altered immunogenicity of swallowed S. mutans in humans by coating native S. mutans antigens with salivary components and/or denaturing surface S. mutans antigens in the acidic environment of the stomach, which would lead to an immune response to modified S. mutans determinants and not to native S. mutans antigens.
变形链球菌存在于大多数人的唾液中，并会被结合在细胞上的唾液成分所修饰。这些与唾液结合的变形链球菌会被吞咽下去，暴露于胃中的高酸度环境中，然后呈递给共同黏膜免疫系统。人们已经付出很多努力来确定黏膜免疫反应所针对的特定变形链球菌抗原。然而，对于黏膜免疫系统所识别的宿主改变的抗原决定簇却知之甚少。研究了在小鼠中胃插管未处理的变形链球菌细胞、包被全人唾液的细胞、用盐酸（pH 2.0）处理的细胞以及包被唾液并经酸处理的细胞的免疫原性。分别通过酶联免疫吸附测定法检测唾液和血清样本中针对未处理或处理过的变形链球菌细胞的免疫球蛋白A（IgA）和免疫球蛋白G（IgG）抗体。总体而言，小鼠针对免疫抗原的唾液IgA和血清IgG抗体水平显著更高（P≤0.05）。此外，检测了12名受试者的人唾液和血清样本中针对未处理或处理过的变形链球菌细胞的天然抗体。在每种情况下，针对包被唾液并经酸处理的细胞的反应性显著更高，其次是包被唾液的变形链球菌。这些结果为以下情况提供了证据：在人类中，通过用唾液成分包被天然变形链球菌抗原和/或在胃的酸性环境中使表面变形链球菌抗原变性，吞咽的变形链球菌的免疫原性发生改变，这将导致对修饰后的变形链球菌决定簇而非天然变形链球菌抗原产生免疫反应。
