Prednisone is used to treat allergies of all kinds, and I think it is a bit nuts that MD's don't think it will affect skin test results. Allergy testing is prone to false negatives and false positives, also, so if I were you, I'd go on symptoms rather than the test results. Also, there is something called Anergy (lack of ability to respond to skin tests) that can affect people with autoimmune disorders, so this may be partly why you didn't respond to the tests also. And finally, sometimes the test serums used are either too old or not in the right concentration (dilution factor) to provoke a reaction. Since there is no standardization on concentration or how long a particular test serum is valid for, the variation from one Allergist's clinic to another will likely result in different test results for the same person at each different Allergy clinic. I've seen this myself - I've been allergy tested at several clinics over the years and have seen different results from each and every clinic. Unfortunately, I get symptoms from many more foods than what show up on the tests, so I consider all the positive readings to be truthful and any that are negative that I get symptoms from are false negatives. I don't have any false positives, since I react to everything that has ever shown up positive. Interestingly, I've been RAST-tested for environmental and food allergies, and the only thing that has ever shown up on a RAST test is birch pollen. Everything else (all the trees, grasses, etc.) has shown negatives in RAST tests despite obvious allergy reactions to those things. My current Allergist tells me the RAST test is less accurate than the skin tests, but in someone on medications that can interfere with the skin tests, the RAST test is the next most accurate as far as allergy tests go. You can also do elimination/challenge testing, but it takes time and the chance of error is high because of the uncontrolled nature of the challenge testing if one does it on one's own at home.
Also, skin and RAST tests won't detect delayed reactivity (type 4 immune reactions) becasue both skin and RAST tests look only for IgE antibodies to the substance being tested. Type 4 tests are IgG mediated and can be every bit as severe as type 1 reactions, but won't show up on the tests.
Bottom line though is if the food causes symptoms, then avoidance is really the best approach. Periodic challenge (maybe once every few years) may reveal the decreasing of symptoms after a while, especially if the allergy is delayed ractivity (type 4 sensitivity, vs. type 1 immediate reactivity).
Gluten & Sulfite Sensitivity, Multiple Food & Inhalant & Medication Allergies, Asthma, Gut issues (dysmotility, non-specific inflammation), UCTD (Lupus?), Osteoporosis, Anemia, Very Low Lymphocyte Counts (T-Cells & B-Cells), malabsorption/malnutrition, etc.
Meds: Pulmicort, Injectable Vitamin B12, Herbs, Nutritional Supplements, Essential Oils, Homeopathy.