This new paper is saying that eczema may not be an IgE allergy but may actually be a delayed or cytotoxic reaction to haptens, smaller molecular components in foods and substances. Er, that’s intolerance then, isn’t it?!
It does make me laugh when researchers state something as new that we have been saying for donkeys, but I suppose it is nice to see it in mainstream papers. The author points out, quite rightly, that:
One has to realize the differences between hypersensitivity reactions to food proteins (allergens capable of initiating immediate hypersensitivity or immune complex reactions) and low-molecular weight compounds (haptens that may initiate cytotoxic reactions or delayed-type allergy).
It is the cytotoxic and delayed reactions that are tested for in non-antibody intolerance tests (not that they are perfect yet by a long shot, but they do at least look for those reactions). Look at ALCAT or the FACT test, for examples. You can read much more about the different types of testing in the free Allergy 101 factsheet.
In clinical practice terms, I have lost count of the number of times I have seen eczema primarily caused by or exacerbated by dairy where no IgE antibody to dairy has been found. That’s a dairy intolerance.
The author goes on to say that these haptens act differently to IgE protein allergens in that, because they are smaller, they can easily go through the mucosa and trigger reactions. Interestingly, the PEG leaky gut test is a good one for establishing what size of molecules your mucosa is allowing through – it tests molecules of different sizes. Based on this article’s theory, a larger number of big molecules points to IgE allergy whereas a large number of smaller molecules points to intolerance. That’s quite a useful way to look at it.
Haptens can be absorbed already through oral mucosa, they don’t undergo digestion and are capable of provoking delayed-type hypersensitivity reactions strongly resembling atopic eczema. Induction of such reactions can be facilitated by cosmetics that frequently contain the same haptens as food.
So, follow the link to read the abstract at least. Consider cytotoxic testing and PEG testing if you have eczema, and make sure you avoid putting your allergens on your skin as well as in your mouth.
Source: Skinsmatter.com newsletter.