Centimeter - 23-7-2004 at 16:23
I have a relative who is severely allergic to some foods. She has had to go to the hospital numerous times do to eating at restaurants. She now does
not eat out anymore because it is possible that her food may be tainted. I asked her if there was some sort of product available that would easily
identify allergens in food; I was surprised to learn that there was not. I am farely sure that an indicator for such allergens is viable, however I
lack the chemistry neccesary to develop one. Thus I seek the aid of more learned individuals. The indicator should be in liquid form and quickly
indicate the presence of allergens by changing color. A seperate solution for each allergen should be created. It should be quite sensitive so that
one would only need to run a plastic wand through the food in order to pick up enough of the allergen to triger the indicator. Any and all assistance
would be most beneficial for society. Thanks!!!
chemoleo - 23-7-2004 at 18:14
I think you are asking for much. You will be hard-pressed to find an assay as you describe.
Allergic problems are mostly related to immunoglobulin A, the antibodies which are found on epithelial cells (cells lining your membranes, such as
lung, gut, skin, etc).
Most allergenic problems are related to auto-immunogenic recognition of proteins that shouldnt be recognised in the first place. In other words, most
likely your relative's immunesystem recognises food proteins as 'foreign', even though they are normal proteins, hence the
immuneresponse.
There are several solutions to this:
1. take immunosuppressive drugs (definitely NOT recommended, as you open the way for infectious diseases)
2. Correct her diet, nail down the cause/type of food causing the problem, and make her not eat it again (trial and error is the only way)
3. get yourself a decent biochemical lab nailing down the problem. This, without a doubt, will have to be done with antibodies. Clearly the lady
produces antibodies she shouldnt, and thus produces an immune reaction - the basis of allergies. The way to test this would be to isolate her
antibodies from her epithelial tissues/blood, and react it with all sorts of foodstuff. The reaction of antibodies with food (biochemical compounds)
can be easily detected). Once these are detected, an in vitro assay could be possibly done.
Be prepared though... this will cost a lot... and unless its a condition that is quite common, there is not much chance on screening food for
allergens as you describe...
Beware though - this is not a medicine forum, and I doubt they could even help you there.
[Edited on 24-7-2004 by chemoleo]
Centimeter - 23-7-2004 at 19:56
I ask not for a medicine. I only want something that she can use to test her food for allergens that she knows she can't tolerate. There could be
one indicator for people who have shellfood allergies and another for people who have peanut allergies and so on. Perhaps there is some chemical that
can be synthesised that will only react with a specific protein (the allergen). Perhaps its reaction with said protein would influence the
system's equilibrium to shift, causing a color change and thus indicating the presence of the allergen. This would allow people who have food
allergies to eat at restaurants w/o worrying about going into anipholactic shock (sp?).
chemoleo - 23-7-2004 at 20:20
Yes it sounds good in theory, but in practise people have all sorts of allergies, against all sorts of proteins. This is not a deterministic science
(equally nature is not deterministic).
The only way to detect this is via antibodies, i.e. whether the blood of your relative contains antibodies that react with food proteins.
Chemicals will rarely work.
There may be specific allergic tests against various proteins/fats (as u mentioned, peanuts, milk proteins and such), and they may well work. If they
are outside the range of what is normally tested, there is not much hope. Its the money that does it, as usual
btw it is anaphylactic shock iirc.
Geomancer - 24-7-2004 at 07:36
I'm sorry to hear about your relative. Such tests are available, but are mainly intended for use by food producers in an industrial setting. A
brief check of Google indicates that the company Neogen makes a product (Reveal) that can detect peanut (and possibly other) allergen in 10 minutes.
But the food has to be processed first with a high speed blender. Depending on the indivual's sensitivity, you might be able to create a packaged
version of the test that contains all the needed stuff in a small package (say, a syringe with a filter and grinding media), and still is sensitive
enough. If you're really interested in going ahead with this (it's a sizable project, with no guarantee of success), I'd suggest
coordinating with one of the food allergy support groups, as well as with the folks at Neogen (or some company with a similar product line). I might
also be interested, please U2U.
Chemistry wise, these tests probably all use some sort of ELISA type technique.
Centimeter - 24-7-2004 at 12:06
What does "U2U" mean?
I am more of a chemist than I biologist, so I have been doing a bunch of research. I now see what you are talking about chemoleo 
. My relative knows exactly what causes her allergies, however she does not always
know when her food contains that allergen. I was under the impression that testing for a specific allergen in one's food would be quite easy
considering the ease by which our bodies detect them and react to them. I was thinking that perhaps we could simulate a miniature allergic reaction.
Would it be at all possible to artificially cultivate a specific antibody? If so, we would then have a base for an indicator. Then all we would need
to figure out is how to make the antibody's response to an allergen visible. Also, can you explain the ELISA technique? Please excuse my
spelling; it IS english after all!
Geomancer - 25-7-2004 at 08:47
ELISA stands for Enzyme Linked Immuno Sorbent Assay. For a basic test for this application, you first acquire antibodies to the allergen you're
interested in. I don't know the details, but you could, say, inject peanut stuff into goats to build up immunity, then isolate the desired
antibody with affinity chromatography. You them prepare a test plate by adsorbing the test sample onto a sorbent plate (these are commercially
available). You incubate the sample loaded plate with your goat anti-peanut antibodies, and then rinse off whatever hasn't reacted. Then you take
commercially available anti-(goat antibody) antibodies, which have an enzyme linked to them, and repeat the incubate/wash procedure. If peanut protein
was present in the sample, you now have a plate with enzyme on it. The linked enzyme is chosen to be easily detected by causing a color change in a
substrate.
It should be clear that ELISA tests are very sensitive to technique. The main difficulty in making a consumer version is minimizing that
sensitivity, as well as reducing the work involved.
U2U (User To User) is the forum's built-in private messanging feature.
TCRN - 26-7-2004 at 15:49
Centimeter,
Do some research on scratch tests, perhaps this is what you are looking for. and also, its IgE not IgA for allergic reactions
chemoleo - 26-7-2004 at 16:14
Well ok I just remembered from courses that IgA is secreted in epithelial tissues. Hence I assumed that this is whats responsible for it.
To quote Alberts (The molecular Biology of the Cell)
IgA is the principal class of a.b. in secretions[i.e. saliva, milk, tears, and respiratory and intestinal secretions).
Conversely, IgE antibodies are loceted on the surface of Mast cells intissues and basophils in the blood. Antigen binding (i.e. peanut proteins)
triggers the cells to secrete a variety of biologically active amines, i.e. histamine - and we all know what anti-histamines are about. So I stand
corrected 
However, apparently IgA also plays a role in the allergic response- or at least it seems to complement some IgE responses.
On the cultivation of antibodies, and the detection thereof - I needn't say more!
Essentially, regarding your poor relative, one would isolate all her antibodies (i.e. from a blood sample) via affinity chromatography. Then they
would be coated onto plastic wells, and all sorts of food extracts would be subjected to it.
Only those that bind (i.e. the allergen) would then be detected by the ELISA assay described by geomancer. Then you'd know which specific foods
to avoid. Unfortuntately this is probably only reproducible for processed foods, as they more or less always contain the same things. For restaurant
foods and such, there is much less hope.
However, there are a number of biotech companies working on just such issues, trying to minimise the effort involved, or that such detections could be
done even yoruself. So maybe there is a little hope...eventually
Morgan - 11-9-2013 at 06:07
I was watching a recent TV segment about a girl who died from eating a treat containing peanuts. After the clip there was a brief mention that that
dry roasting peanuts might be causing more attacks. So over a week later I started to wonder why that might be and came across this article.
http://www.cbsnews.com/8301-204_162-57596190/13-year-old-die...
Effects of cooking methods on peanut allergenicity.
http://www.ncbi.nlm.nih.gov/pubmed/11398088
Tidbit
"Even a peanut-allergic physician specializing in allergy and immunology suffered a severe reaction when another allergist gave him homemade cookies
that were described as completely free of peanuts. Only they weren't. The cookies were removed from the cookie sheet with a spatula that had been used
on other cookies containing peanuts, and the spatula was not washed between batches."
Dodging Peanuts: To Some, a Lifelong Challenge
http://www.nytimes.com/learning/teachers/featured_articles/2...