KCL: Ancient antibody molecule offers clues for allergy treatment

Research lead

Researchers at the Randall Division of Cell & Molecular Biophysics, King’s College London. UK, have discovered that a molecule that is an essential antibody in the chicken immune system behaves quite differently from its human counterpart, throwing light on the origin and cause of allergic reactions in humans and giving hope for new strategies for treating allergies. 

One of the researchers, Alex Taylor, said the antibody, IgY, is like a living fossil. “By studying this molecule, we can track the evolution of allergic reactions back to at least 160 million years ago, and by looking at the differences between the ancient and the modern antibodies we can begin to understand how to design better drugs to stop allergic reactions in their tracks.”

The chicken IgY looks remarkably similar to its human counterpart, IgE.  IgE is known to be involved in allergic reactions and humans also have a counterpart antibody called IgG that helps to destroy invading viruses and bacteria. Scientists know that both IgE and IgG were present in mammals around 160 million years ago because the corresponding genes are found in the recently published platypus genome. But in chickens there is no equivalent to IgG, and so IgY performs both functions.

Researcher Rosy Calvert said, “Although these antibodies all started from a common ancestor, for some reason humans have ended up with two rather specialised antibodies, whereas chickens only have one that has a much more general function.”

In humans, IgE binds extremely tightly to white blood cells causing an over-reaction of the immune system. The researchers have found that IgY behaves in a similar way to the human IgG, which is not involved in allergic reactions and binds much less tightly to white blood cells.

In the next stage of the project the researchers will examine the interaction between the antibodies and the surface of the white blood cell. This is with a view to designing drugs that could alter this interaction and therefore “loosen” the binding of IgE, making it more like its chicken counterpart.