Atopy
| Atopy | |
|---|---|
| Other names | Atopic syndrome |
Eczema—a typical atopic manifestation | |
| Pronunciation | |
| Specialty | Dermatology, immunology |
Atopy is the tendency to produce an exaggerated
Atopy may have a hereditary component, although contact with the allergen or irritant must occur before the hypersensitivity reaction can develop (characteristically after re-exposure).[3] Maternal psychological trauma in utero may also be a strong indicator for development of atopy.[4]
The term atopy was coined by Arthur F. Coca and Robert Cooke in 1923.[5][6] Many physicians and scientists use the term "atopy" for any IgE-mediated reaction (even those that are appropriate and proportional to the antigen), but many pediatricians reserve the word "atopy" for a genetically mediated predisposition to an excessive IgE reaction.[7] The term is from Greek ἀτοπία meaning "the state of being out of place", "absurdity".[8]
Signs and symptoms
Atopic sensitization is considered IgE positivity or prick test positivity to any common food- or air-borne allergen.
Allergic reactions can range from sneezing and rhinorrhoea to anaphylaxis and even death.[13]
Pathophysiology
In an allergic reaction, initial exposure to an otherwise harmless exogenous substance (known as an allergen) triggers the production of specific IgE antibodies by activated B cells.
Causes
Atopic reactions are caused by localized hypersensitivity reactions to an allergen. Atopy appears to show a strong hereditary component. One study concludes that the risk of developing atopic dermatitis (3%) or atopy in general (7%) "increases by a factor of two with each first-degree family member already suffering from atopy".[14] As well, maternal stress and perinatal programming is increasingly understood as a root cause of atopy, finding that "...trauma may be a particularly robust potentiator of the cascade of biological events that increase vulnerability to atopy and may help explain the increased risk found in low-income urban populations."[4]
Environmental factors are also thought to play a role in the development of atopy, and the 'hygiene hypothesis' is one of the models that may explain the steep rise in the incidence of atopic diseases, though this hypothesis is incomplete and in some cases, contradictory to findings.[4] This hypothesis proposes that excess 'cleanliness' in an infant's or child's environment can lead to a decline in the number of infectious stimuli that are necessary for the proper development of the immune system. The decrease in exposure to infectious stimuli may result in an imbalance between the infectious-response ("protective") elements and the allergic-response ("false alarm") elements within the immune system.[15]
Some studies also suggest that the maternal diet during pregnancy may be a causal factor in atopic diseases (including asthma) in offspring, suggesting that consumption of antioxidants, certain lipids, and/or a Mediterranean diet may help to prevent atopic diseases.
A Swedish research study titled "Atopy In Children Of Families With An Anthroposophic Lifestyle" comparing the rate of bronchial asthma, allergies, dermatitis, and other atopic diseases among Steiner school pupils and pupils in public schools originally appeared in the May 1, 1999, edition of the British medical journal The Lancet. The findings indicated that Steiner school pupils were "at a significantly lower risk of atopy" than children attending public schools. The researchers investigated a variety of factors in the lives of the Steiner school pupils that might have contributed to this lower rate of atopy, which included breastfeeding, reduced immunization, avoidance of antibiotics and medications that reduce fevers, consumption of bio-dynamic and organic foods, and other physical aspects of the children's lives. [16]
The multicenter PARSIFAL study in 2006, involving 6,630 children age 5 to 13 in 5 European countries, suggested that reduced use of antibiotics and antipyretics is associated with a reduced risk of allergic disease in children.[17]
Genetics
There is a strong genetic predisposition toward atopic allergies, especially on the maternal side. Because of the strong familial evidence, investigators have tried to map susceptibility genes for atopy.
Staphylococcus aureus
Bleach baths provide temporary control of eczema.
Changes in prevalence over time
In adults, the prevalence of IgE sensitization to allergens from house dust mite and cat, but not grass, seems to decrease over time as people age.[29] However, the biological reasons for these changes are not fully understood.
Treatments
Treatments for atopic disorders depend on the organ(s) involved. They can vary from local treatment options, often topical corticosteroids, to systemic treatment options with oral corticosteroids, biological treatments (e.g. omalizumab, mepolizumab) or allergen immunotherapy.[30][31][32]
See also
- Eczema
- Asthma
- Rhinitis
- Anaphylaxis
- Allergic march
References
- ^ Merriam-Webster Dictionary: Atopy
- ^ OCLC 1040673074.)
{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link - ^ "Mosby's Medical Dictionary:atopy". Archived from the original on 2011-07-10.
- ^ PMID 19838310.
- ^ Coca AF, Cooke RA. (1923) On the classification of the phenomenon of hypersensitiveness J Immunol
- ISBN 978-3-540-23133-2. Retrieved 4 May 2010.
- ISBN 978-4-431-88314-2. Retrieved 4 May 2010.
- ^ "atopy". Online Etymology Dictionary. Douglas Harper. 2019. Retrieved 26 Sep 2019.
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- ^
Küster, W.; Petersen, M.; Christophers, E.; Goos, M.; Sterry, W. (December 12, 2004). "A family study of atopic dermatitis". Archives of Dermatological Research. 282 (2 / January, 1990): 98–102. S2CID 9396200.
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- PMID 16387585. Archived from the original (PDF) on 2007-09-27. Retrieved 2007-07-18.)
{{cite journal}}: CS1 maint: multiple names: authors list (link - S2CID 30698973.
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External links
- Case Studies in Environmental Medicine (CSEM): Environmental Triggers of Asthma – Agency for Toxic Substances and Disease Registry, U.S. Department of Health and Human Services.