Researchers have discovered the earliest antibodies in the animal kingdom, in the immune systems of fish guts.
The findings provide valuable insight into human immunity, as well as promising new developments in keeping fish safe from pathogens.
Compared to birds or mammals, fish lack certain immunoglobins, such as IgA, instead using IgT in their intestines. Crucially, both IgA and IgT utilise similar systems to maintain health, suggesting that further study of IgT will reveal ways that our own intestinal immunity works.
Furthermore, the findings should have great effect on fish health and vaccines, as the last few decades of research have missed out the contribution of IgT in aiding fish immunity.
It is currently thought that specialisations between species have occurred independently through convergent evolution, driven through similarities in the selective pressures that act upon the guts of amphibians, mammals and fish.
The findings fly in the face of previous suppositions that immunoglobin isotypes formed specialised roles into different parts of the body during the evolution of tetrapods, or four-legged animals.
While IgT had been discovered some five years ago, its role had until now remained obscure.
The team of researchers behind the discovery concluded that the specialisation into specific body regions by immunoglobin isotypes is found in the immune systems of all vertebrates with jaws – fish previously being excluded.
For further information see: IgT, a primitive immunoglobin class specialised in mucosal immunity: Nature Immunology : Nature Publishing Group.