Weinstein P D, Mage R G, Anderson A O
ARD, USAMRIID, Ft. Detrick, Frederick, MD 21702.
Adv Exp Med Biol. 1994;355:249-53. doi: 10.1007/978-1-4615-2492-2_42.
In this paper we present genomic DNA sequence and histological evidence that the appendix is a site of diversification of the rabbit's primary antibody repertoire. By 6 weeks after birth, the B cell follicular regions of the rabbit appendix and the distribution of the resident lymphoid cells bear a strong morphological resemblance to similar regions within two primary lymphoid tissues, the chicken bursa and the sheep ileal Peyer's patch. However, similarities between the rabbit appendix, chicken bursa and sheep ileal Peyer's patch end as these animals reach adulthood. The rabbit appendix undergoes morphological and cellular distribution changes as it matures taking on the appearance of a secondary lymphoid tissue, while the sheep ileal Peyer's patch and the chicken bursa both involute. We determined DNA sequences of PCR amplified rearranged variable region genes from germinal center B cells of 6 week old rabbits isolated from several different appendix dark zones and light zones. There was a trend toward a higher degree of diversification from the germ-line VH gene DNA sequence in dark zones than light zones. It is likely that both gene conversion and somatic hypermutation are responsible for the nucleotide changes we observed. Our findings suggest that the rabbit appendix functions as a mammalian bursal equivalent early in development. As the rabbit matures, the appendix appears to evolve into a secondary lymphoid tissue resembling secondary GALT in appearance and possibly in function.
在本文中，我们提供了基因组DNA序列和组织学证据，证明阑尾是兔子主要抗体库多样化的一个位点。出生后6周时，兔子阑尾的B细胞滤泡区域以及常驻淋巴细胞的分布与两种主要淋巴组织（鸡法氏囊和绵羊回肠派伊尔结）内的相似区域在形态上有很强的相似性。然而，随着这些动物成年，兔子阑尾、鸡法氏囊和绵羊回肠派伊尔结之间的相似性就消失了。兔子阑尾在成熟过程中会发生形态和细胞分布变化，呈现出二级淋巴组织的外观，而绵羊回肠派伊尔结和鸡法氏囊都会退化。我们测定了从几只不同兔子阑尾暗区和亮区分离出的6周龄兔子生发中心B细胞中PCR扩增的重排可变区基因的DNA序列。与亮区相比，暗区的种系VH基因DNA序列有更高程度的多样化趋势。我们观察到的核苷酸变化可能是由基因转换和体细胞超突变共同导致的。我们的研究结果表明，兔子阑尾在发育早期发挥着相当于哺乳动物法氏囊的功能。随着兔子成熟，阑尾似乎演变成一种二级淋巴组织，在外观上类似于二级肠道相关淋巴组织，功能上可能也相似。
