Here’s a really well-done and interesting study: Association between severity of atopic eczema and degree of sensitization to aeroallergens in schoolchildren. (So much great dermatological research coming out of Germany these days.) If you click on the link, a wealth of related research pops up to the right.
Conclusion of the above study: “The degree of sensitization is directly associated with the severity of atopic eczema. We speculate that early epicutaneous sensitization to aeroallergens may be enhanced by damage of the skin barrier function. The specific IgE response seems to contribute to the severity of the disease in a dose-dependent fashion.”
It’s another reason to follow our grandparents’ (and Dr. Brazelton’s) advice to use soaps, not detergents, with babies, as detergents can cause a significant increase in skin membrane permeability (which would degrade the skin barrier function), unnaturally increase antigen penetration, and could cause sensitization per this paper, especially in babies who have such naturally permeable skin.
I am left to wonder if another interpretation of the study could be thus:
Given the association I have observed between atopic eczema and detergent reactions, with the severity of eczema being proportional to detergent strength and exposure; and given that detergents increase skin membrane permeability and antigen penetration; and given that detergents are ubiquitous in modern environments, and that what people have been washing with would affect the state of the skin during such a test (the skin changes over the course of months when detergents are eliminated from the home environment, i.e., removal of the detergents from the skin prior to the testing is unlikely to happen, and even if done, it takes months for the skin to normalize):
then it seems to me that the severity of eczema could indicate level of detergent exposure in the study population, which would also then be directly related to antigen load. Those with the most detergent would have the greatest compromise of the skin barrier, greatest antigen load, and greatest sensitization.
In other words, could the degree of sensitization noted in the study be the result of IMMEDIATE effects caused by detergent reactions, rather than just past sensitization (presumably because of the eczema’s effects on the skin barrier)? Or could it be the result of both past and immediate effects? Both are plausible, but knowing the answer definitively makes a difference in how the eczema and allergies might be prevented.
Additionally, the paper would not have taken into account the prevalence of detergents in modern household dust and the increased penetration of aeroallergens in lung tissue as a result. (In other words, the sensitization may not be through cutaneous exposure alone.)
Much of this and related research supports my theory that the eczema reaction may be a warning mechanism by the immune system, similar to the pain response for the nervous system. (See The Big Picture post earlier in this blog.) If the immune system is unnaturally loaded with antigen, it may benefit from “asking” the conscious brain to avoid allergens.