Nossal G J, Abbot A, Mitchell J, Lummus Z
J Exp Med. 1968 Feb 1;127(2):277-90. doi: 10.1084/jem.127.2.277.
This paper describes the trapping of antigen in lymphoid follicles of rat popliteal lymph nodes as revealed by electron microscopic radioautographs following injection of (125)I-labeled Salmonella adelaide flagella and other materials. The antigen was taken up vigorously, and to an approximately equal extent, by both primary and secondary follicles. The rate of uptake was faster in preimmunized than in virgin adult rats. The bulk of the antigen in follicles was extracellular, and persisted in this location for at least 3 wk. Label was most frequently found at or near the surface of fine cell processes. Many of these were branches of dendritic follicular reticular cells. Such processes interdigitated with equally fine processes of lymphocytes, creating an elaborate meshwork. In some cases, antigen was found between lymphocytes which appeared to be in close apposition. Occasionally, a few grains appeared over lymphocyte nuclei and study of serial sections suggested that this probably represented true entry of small amounts of antigen into lymphocytes. The characteristic "tingible body" macrophages (TBM) of germinal centers appeared to play only a secondary role in follicular antigen retention. They showed degrees of labeling over their phagocytic inclusions varying from negligible to moderately heavy. Moreover, follicles lacking or poor in TBM retained antigen just as effectively as those containing numerous TBM. The hypothesis is advanced that TBM may be derived from monocytes that migrate down from the circular sinus. Follicular localization of three other materials was also studied, though not in such detail. These were (125)I-HSA complexed to anti-HSA: (125)I-labeled autologous IgG; and (125)I-monomeric flagellin. All of these showed the basic features of intercellular, membrane-associated deposition noted with (125)I-flagella. The role of follicular antigen depots in immune induction is discussed. The tentative conclusion is reached that follicular antigen in a primary follicle encounters natural antibody on the surface of certain antigen-reactive lymphocytes. The resultant reaction causes blast cell transformation and eventually the genesis of a germinal center.
本文描述了注射（125）I标记的阿德莱德沙门氏菌鞭毛及其他物质后，通过电子显微镜放射自显影揭示的抗原在大鼠腘淋巴结淋巴滤泡中的捕获情况。抗原被初级滤泡和次级滤泡强烈摄取，且摄取程度大致相等。免疫前大鼠的摄取速率比未免疫成年大鼠更快。滤泡中的大部分抗原位于细胞外，并在该位置持续存在至少3周。标记最常出现在细细胞突起的表面或其附近。其中许多是树突状滤泡网状细胞的分支。这些突起与淋巴细胞同样纤细的突起相互交错，形成一个精细的网络。在某些情况下，抗原出现在似乎紧密相邻的淋巴细胞之间。偶尔，淋巴细胞核上会出现一些银粒，连续切片研究表明，这可能代表少量抗原真正进入了淋巴细胞。生发中心特征性的“含铁血黄素”巨噬细胞（TBM）在滤泡抗原保留中似乎仅起次要作用。它们吞噬内含物上的标记程度从可忽略不计到中等程度不等。此外，缺乏TBM或TBM较少的滤泡与含有大量TBM的滤泡一样有效地保留了抗原。有人提出假说，TBM可能源自从环状窦向下迁移的单核细胞。还对其他三种物质的滤泡定位进行了研究，但细节程度较低。它们是与抗人血清白蛋白（HSA）结合的（125）I-HSA、（125）I标记的自体IgG和（125）I单体鞭毛蛋白。所有这些都显示出与（125）I-鞭毛相关的细胞间、膜相关沉积的基本特征。讨论了滤泡抗原库在免疫诱导中的作用。初步得出结论，初级滤泡中的滤泡抗原会遇到某些抗原反应性淋巴细胞表面的天然抗体。由此产生的反应导致母细胞转化，最终形成生发中心。
