Global Biotherapeutics Technologies, Pfizer Inc., Foresterhill, Aberdeen AB25 2ZS, United Kingdom.
Dev Comp Immunol. 2012 Apr;36(4):665-79. doi: 10.1016/j.dci.2011.10.007. Epub 2011 Oct 20.
The cartilaginous fish (chimeras, sharks, skates and rays) are the oldest group relative to mammals in which an adaptive immune system founded upon immunoglobulins has been found. In this manuscript we characterize the immunoglobulins of the spiny dogfish (Squalus acanthias) at both the molecular and expressed protein levels. Despite the presence of hundreds of IgM clusters in this species the serum levels of this isotype are comparatively low. However, analysis of cDNA sequences and serum protein suggests microheterogeneity in the IgM heavy chains and supports the proposal that different clusters are preferentially used in the two forms (monomer or pentamer) of this isotype. We also found that the IgNAR isotype in this species exists in a previously unknown multimeric format in serum. Finally, we identified a new form of the IgW isotype (the shark IgD orthologue), in which the leader is spliced directly to the first constant domain, resulting in a molecule lacking an antigen-binding domain.
软骨鱼（包括腔棘鱼、鲨鱼、鳐鱼和魟鱼）是相对于哺乳动物而言最古老的一类动物，在它们体内发现了以免疫球蛋白为基础的适应性免疫系统。在本研究中，我们在分子和表达蛋白水平上对棘鲛（Squalus acanthias）的免疫球蛋白进行了研究。尽管在该物种中存在数百个 IgM 簇，但这种同种型的血清水平相对较低。然而，对 cDNA 序列和血清蛋白的分析表明，IgM 重链存在微异质性，并支持这样的假设，即不同的簇优先用于这种同种型的两种形式（单体或五聚体）。我们还发现，该物种的 IgNAR 同种型以一种以前未知的多聚体形式存在于血清中。最后，我们鉴定了一种新形式的 IgW 同种型（鲨鱼 IgD 同源物），其中的前导序列直接拼接至第一个恒定区，导致该分子缺乏抗原结合区。
