Reynaud C A, Mackay C R, Müller R G, Weill J C
Basel Institute for Immunology, Switzerland.
Cell. 1991 Mar 8;64(5):995-1005. doi: 10.1016/0092-8674(91)90323-q.
Ileal Peyer's patches (IPPs) in the sheep are composed of tightly packed follicles in which surface IgM-positive B cells proliferate and can be exported to the periphery. We report that the light chain rearrangement pattern in a single IPP follicle is much more restricted than in the entire tissue, which indicates that, as in the chicken bursa, ongoing rearrangement does not take place in this organ. Moreover, we show that B cells extensively diversify their antigen receptor while proliferating in IPP follicles. Sequencing of part of the V lambda locus indicates that this diversification is not achieved by gene conversion, but rather by untemplated somatic mutation and intense selective pressure. These results strongly imply that sheep IPPs behave as a bursa-equivalent, primary lymphoid organ of diversification and that somatic point hypermutation, which is known to proceed during secondary immune responses, can also generate an antibody repertoire.
绵羊的回肠派伊尔氏结（IPP）由紧密排列的滤泡组成，其中表面IgM阳性B细胞在滤泡中增殖并可输出至外周。我们报告称，单个IPP滤泡中的轻链重排模式比整个组织中的受限得多，这表明，与鸡法氏囊一样，该器官中不会发生正在进行的重排。此外，我们表明B细胞在IPP滤泡中增殖时会使其抗原受体广泛多样化。Vλ基因座部分的测序表明，这种多样化并非通过基因转换实现，而是通过无模板的体细胞突变和强烈的选择压力实现。这些结果有力地表明，绵羊IPP起着法氏囊等效物的作用，是一个多样化的初级淋巴器官，并且已知在二次免疫反应期间发生的体细胞点突变也可以产生抗体库。
