Help Needed Understanding Allergy ELISA Results

[Steven Joseph Szarka]

Several members of my family have had ELISA tests done to screen for 
blood IgG4 and IgE against a list of potential food allergens. The 
results were presented in tabular form with a numerical values attached 
to each food sample. The results are then divided into 4 columns 
depending on the numerical rating: 

1. essentially no detection
2. low  (10-50)
3. intermediate (50-300)
4. High (300-3000)

To help understand what foods (all, certain, or none) should be avoided I 
have the following questions:

1. Does any amount of detectable IgE indicate a food allergy or is there 
a cut-off (eg. only those in the high column)? If there is a cut-off; is 
it arbitrary or physiologically based?

2. I assume the RAST (Radioactive equivalent?) is more sensitive; is this 
higher sensitivity necessary to identify all allergies?

3. Would continual exposure to a low reactive food item increase the IgE 
signal so that eventually it moves into the 'high' category and becomes a 
problem (assuming the 'low' foods are presently not a problem)?

4. Based on the experience of people who perform these tests; what is the 
ELISA pattern generally seen in the population?
Do most people show:

i. no reaction
ii. low reaction to many items
iii. a high reaction to a few items combined with either i. or ii.

5. Is the response to question 4 different for children compared to adults?

Thanks to all those who can offer information
Steve



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Steven Szarka                              Botany Division
                                           Dept. of Biological Sciences      
Email: sjszarka at acs.ucalgary.ca            University of Calgary             
FAX: (403) 289-9311                        2500 University Drive NW          
Phone: (403) 220-7907                      Calgary, AB, Canada T2N 1N4      
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