IgT, a primitive immunoglobulin class specialized in mucosal immunity.
IgT, a primitive immunoglobulin class specialized in mucosal immunity.
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硬骨鱼是含有免疫球蛋白的最原始的骨脊椎动物。与哺乳动物和鸟类相比，这些物种缺乏免疫球蛋白 A (IgA) 或功能等同物。这一观察结果表明，在四足动物进化过程中，免疫球蛋白同种型专门化为粘膜和全身反应。为了挑战这一范式，我们在这里证明了 IgT（一种功能未知的免疫球蛋白同种型）的作用类似于粘膜抗体。我们仅在肠道中检测到虹鳟鱼 IgT 对肠道寄生虫的反应，而 IgM 反应仅限于血清。大多数肠道细菌都被 IgT 覆盖。由于 IgT 和 IgA 是系统发育上距离较远的免疫球蛋白，因此它们对粘膜反应的专门化可能是通过趋同进化过程独立发生的。
Teleost fish are the most primitive bony vertebrates that contain immunoglobulins. In contrast to mammals and birds, these species are devoid of immunoglobulin A (IgA) or a functional equivalent. This observation suggests that specialization of immunoglobulin isotypes into mucosal and systemic responses took place during tetrapod evolution. Challenging that paradigm, here we show that IgT, an immunoglobulin isotype of unknown function, acts like a mucosal antibody. We detected responses of rainbow trout IgT to an intestinal parasite only in the gut, whereas IgM responses were confined to the serum. IgT coated most intestinal bacteria. As IgT and IgA are phylogenetically distant immunoglobulins, their specialization into mucosal responses probably occurred independently by a process of convergent evolution.