van der Waaij L A, Limburg P C, Mesander G, van der Waaij D
Department of Medical Microbiology, University of Groningen, Netherlands.
Gut. 1996 Mar;38(3):348-54. doi: 10.1136/gut.38.3.348.
The bacterial flora in the human colon, although extremely diverse, has a relatively stable composition and non-infectious anaerobic bacteria are dominant. The flora forms a pool of numerous different antigens separated from mucosal immunocompetent cells by just a single layer of epithelial cells. Despite this thin barrier, however, the colonic mucosa is physiologically only mildly inflamed. This study looked at the mucosal humoral immune response against faecal anaerobes. By flow cytometric analysis the in vivo immunoglobulin coating of anaerobic bacteria in faecal samples of 22 healthy human volunteers was determined. In a previous study flow cytometric analysis of faecal bacteria has been found to be a very sensitive method to detect immunoglobulins on faecal bacteria. This technique showed that in vivo many bacteria are coated with IgA (24-74%) and less with IgG and IgM. The presence of many bacteria coated with IgA implies that IgA coating does not result in permanent removal of the species from the colon. The absence of immunoglobulin coating suggests that there is immunological unresponsiveness for anaerobic bacterial antigens. It is concluded that both immunological unresponsiveness and preferential coating with IgA are responsible for the relative absence of colonic mucosal inflammation.
人类结肠中的细菌群落虽然极其多样，但其组成相对稳定，且非感染性厌氧菌占主导地位。该细菌群落形成了一个由众多不同抗原组成的库，这些抗原与黏膜免疫活性细胞仅隔着一层上皮细胞。然而，尽管这层屏障很薄，但结肠黏膜在生理上仅有轻微炎症。本研究观察了针对粪便厌氧菌的黏膜体液免疫反应。通过流式细胞术分析，测定了22名健康人类志愿者粪便样本中厌氧菌的体内免疫球蛋白包被情况。在之前的一项研究中，已发现粪便细菌的流式细胞术分析是检测粪便细菌上免疫球蛋白的一种非常灵敏的方法。该技术表明，在体内许多细菌被IgA包被（24% - 74%），被IgG和IgM包被的较少。许多被IgA包被的细菌的存在意味着IgA包被并不会导致该菌种从结肠中被永久清除。缺乏免疫球蛋白包被表明对厌氧细菌抗原存在免疫无反应性。得出的结论是，免疫无反应性和IgA的优先包被共同导致了结肠黏膜炎症相对较轻的情况。
