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Pony midge study offers allergy clues

Shetland ponies’ immune response to insect bites could help scientists prevent people developing allergies, a study shows.

University researchers have shown the horse immune system can respond to midge bites in a way that prevents - rather than triggers - allergic reactions.

The ponies’ immune response to bites is similar to what happens in people with allergies.

Understanding what triggers allergic reactions could help researchers come up with ways to stop people developing sensitivities.

Immune reactions

It was previously thought that ponies which do not suffer reactions to bites do so because their immune system does not recognise allergens carried by the insects.

The team found all horses respond and that their immune system can act in two different ways.

One response produces allergy symptoms - such as itching and inflammation - while the other prevents an allergic reaction.

Protective response

After being exposed to midges, the horse immune system can release factors - known as cytokines - which affect the behaviour of other cells.

Ponies that react to midge bites release cytokines - known as IL-4 - which trigger allergy symptoms.

In ponies not sensitive to bites, another cytokine, INF-gamma, is released, which blocks cells that would otherwise trigger allergic reactions.

Preventing allergies

By priming the human immune system to respond in a way that does not trigger reactions, it could be possible to prevent people developing sensitivities.

Allergies are caused by complex interactions between genetic and environmental factors.

The reason why some individuals develop sensitivities, while others do not, is not fully understood.

The study, published in the journal PLOS ONE, was funded by the Dutch Foundation for Technical Sciences (STW) and was carried out in collaboration with researchers in the Netherlands.

We believe this finding could have direct practical implications, for example by helping immune responses to choose the “right” direction in individuals who we would like to protect from developing occupation-associated allergies.

Dr Dietmar ZaissSchool of Biological Sciences