I have been in the allergy field for over 30 years. I do allergy SKIN TESTING and have had many patients over the years come in with their allergy BLOOD TESTING results. I have had VERY little correlation in the results! I have asked about as many people in the know as I could and have yet to get a definitive answer as to why the results are SO different between the blood results and the skin results.
The closest thing to a reasonable explanation was from a graduate student in Immunology. She said that the skin has more sensitive Histamine receptor sites, therefore the skin market testing is more reliable.