What are they and what are they for?

People with allergies - to house dust, say, or cats or grass pollens - make antibodies to these things in their blood. These are known as IgE antibodies. Thus, people with hayfever will have special IgE antibodies to grass pollens, those with cat allergy will have antibodies to cat allergens etc.

Quite a lot of people without obvious allergies also make these antibodies.

People who make such antibodies - about 35% of the British population - are described as 'atopic'. Remember, making antibodies of itself is not a disease or illness. It is only a problem if there is an allergy with it.

You can measure these antibodies in blood samples - or by using a technique called skin prick testing. In these tests, a small drop of allergen solution is put on the skin of the forearm and pricked through using a very fine point. If the person has antibodies to the allergen then a small, itchy bump will appear over about ten minutes. It feels exactly like a nettle sting and goes away just as quickly. If the person has no antibodies then there will be no bump.

These tests are very safe. They have been done on millions of children and adults around the world without causing any problems. If you don't have antibodies then skin prick tests will not make you produce them - even if you have lots of tests.

What did we do in Ashford?

Children don't start to make IgE antibodies to dust allergens in the air until they are about 4-5 years old. We didn't do the first skin prick tests in Ashford until the children were aged 5-6. We did most of the tests at school - using drops of house dust mite, cat and grass pollen allergens. Almost all the children were very brave about this - although we had a few tears!

We also tested their parents! This was to find out whether they were 'atopic' - because we know that allergies and atopy tend to run in families.

What did we find in Ashford?

About a third of the Ashford parents had one or more positive responses to the skin tests. Men were slightly more likely to do so than women.

Many fewer children had a positive responses - this is as we would expect since they are of course much younger.

About one third of mothers and fathers had a positive skin prick test - but only one in six of the five year olds percentage of mothers, fathers or children

Children were about equally likely to have a positive test to cat fur as to grass pollen or house dust mite.

At the age of five, about 10% of the Ashford study children had a positive skin prick test to cat or grass or house dust mite percentage of Ashford study children with a positive test skin prick test solution

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