Thanks Salamandaral,
I had the blood test as a result of a skin rash on my lower legs after playing golf in shorts. It went in 24 hours but it was not the first time it had occurred so I went to see the doc. I am well, get less illnesses than most and have no other symptoms. I have had friends whose immune system has been damaged through (allegedly) toxic air so I was a bit concerned when I learned that it had to do with the immune system. I am due to talk to my GP again in a couple of weeks. Thanks for the heads up.