It is now established that allergy is more common in developed countries than developing countries and similarly it is more in urban than rural area.
This is a very complicated question that several researchers are focusing their entire careers on, so I certainly don't think there's an easy definitive answer. There are a number of compelling hypotheses that come to mind:
Some version of the hygiene hypothesis, which suggests that increased exposure to pathogens, particularly helminths, in developing countries/rural populations results in the development of regulatory cells that help to reduce allergies.
Vitamin D deficiency, which is more prevalent in urban populations in developed countries, has been associated with the severity of allergic diseases and proposed to be a major factor.
Commensal microflora have been found to contribute to systemic immune effects, and differences in the microbiota arising from geographical/dietary/antibiotic usage differences have been proposed to affect the incidence of allergies.
As with most scientific hypotheses, in the case of all these hypotheses some studies have provided supporting data while others have reported opposing data.
This is a very complicated question that several researchers are focusing their entire careers on, so I certainly don't think there's an easy definitive answer. There are a number of compelling hypotheses that come to mind:
Some version of the hygiene hypothesis, which suggests that increased exposure to pathogens, particularly helminths, in developing countries/rural populations results in the development of regulatory cells that help to reduce allergies.
Vitamin D deficiency, which is more prevalent in urban populations in developed countries, has been associated with the severity of allergic diseases and proposed to be a major factor.
Commensal microflora have been found to contribute to systemic immune effects, and differences in the microbiota arising from geographical/dietary/antibiotic usage differences have been proposed to affect the incidence of allergies.
As with most scientific hypotheses, in the case of all these hypotheses some studies have provided supporting data while others have reported opposing data.
Although not working in the field currently, I am especially interested in the hygiene hypothesis and the effect of helminth infections on immune regulation. I know of studies using helminths to control autoimmune diseases, particularly Crohn's Disease, with reported great success.
I wonder if anyone has looked at the historic incidence of allergic disorders in developed countries as they went from less developed to more developed. I am sure there are countries currently undergoing this type of process that could be studied. Admittedly, it would take a long time to get real data; probably at least a few generations.
This point has been researched extensively by David Pritchard in the UK. Look up his experiments on Hookworms and asthma.
I would add another point beside hygiene hypothesis. Hygiene hypothesis is obviously responsible for this. However this is also depends on healthcare system. In developing countries not all people are aware of allergies which are not severe in their actions. So lots of cases are not being registered in healthcare system in developing countries. If you compare you will find healthcare system of developed countries is much better than that of developing countries. Every cases are being registered in the database. So percentage of affected people will normally be higher in developed countries than that of developing countries.
I am from a developing country I can give you hundred of examples where people don´t visit doctor though they are having allergies. If you go to village area, you will find a lot of childrens experienced with allergies but none of those cases are registered in healthcare system. This is because there is no database exist. Most the cases they visit doctor personally. Sometimes they buy medicine by themselves. So there is no way track down the number of patient those have allergies.
This could be one possible explanation why allergies is high in developed countries.
immunologist dirty secret: hygiene hypothesis, immune tolerance, role of mast cell and macrophage sub-types and finally the Treg cell roles
A major decrease in Type 1 Responses because of decreased infections - increase sanitation has resulted in an increase in Type 2 Responses that are responsible for most allergies. The products of Type 1 (e.g., IFN-g) and Type 2 (e.g., IL-4) reciprocally down regulate each other.
In the attached reference, you will find some strategic observations with experimental explanations on the hygiene hypothesis.
Yes the concept of hygiene theory will play a good role here and at the same time considering the attached document by Chris Drouet as an essential ingredient to answer this question.
Same reason more autoimmune diseases are prevelant in developed countries. We are exposed less to bacteria and viruses early in life that help shape our immune systems. Hence being "too clean" is not good. I like using the phrase "a little bit of dirt is good for you".
The hygiene theory might be important. I suppose that detergents used by cleaning the bed of the child, and used when washing might be also important, because detergents reaching the gastrointestinal tract, and reaching the blood might influence the development of the immune system.
This is indeed a complicated situation with no simple or straightforward answer. I suspect that it is a combination of all of the above responses. Bottom line is that western/developed countries are a semi sterile environment. We are as a result loosing our immunological capacity. My allergy training has always stressed the importance that all kids should spend time in rural communities exposed to a variety of allergens to increase our ability to respond to challenges. There is a distinct difference between farm kids and city kids with an increasing prevalence of asthma and allergy seen in school age children. We do not see the same situation in 3rd world countries. I suspect that an increase exposure to a variety of allergens, bacteria, helminths and different food sources and less exposure to agricultural/industrial chemicals, antibiotics and hormones all have an important influence that result in less allergy in developing countries.
I Completely agree with you. In the same time I suppose, that detergents used by washing our dishes and for instance the bed of the baby (who is taking everything in his mouth) might get into the body in a small amount. If it happens, the membrane fluidity of immune cells will be influenced leading to the disturbed immunity. Unfortunately scientific data investigating this possibility are missing. In Hungary the prevalence of atopic dermatitis is high not only in industrialized towns, but also in agricultural regions ( Kuhnyar, A., K. Egyud, et al. (2006). "Prevalence of atopic dermatitis among children under 19 in an East-Hungarian agricultural county." Clin Dev Immunol 13(2-4): 395-399.
Hello, the attached review adds an evolutionary perspective to the problem. Hope you will enjoy it
Likely various environmental factors are interfering with the immune system and immune system development, including the ones mentioned here. I'd also point out that environmental chemicals are an important environmental factor that can affect the immune system and are linked to allergies (e.g., see http://www.ncbi.nlm.nih.gov/pubmed/20976153). Chemical exposure levels are generally higher in developed countries.
All the suggestions, regarding allergy in developed countries are interesting and some are reasonable. Hygiene theory that has been mostly suggested seems to be very much acceptable in this regard. Not only the allergy, autoimmune diseases like multiple sclerosis, Type-1 diabetes(insulin-dependent diabetes mellitus), Crohn’s disease are also increasing day by day in developed countries. Few suggestions of use chemicals and detergent are notable. Vitamin D deficiency might not be responsible because if it is true Muslim women using hejab or Borkha should suffer more. Most visitors from developed countries to developing countries suffer from diarrhoeal diseases consuming same water which has no effect on the natives. My nephew, born in Bangladesh but grown in USA always try to avoid visiting our country with his parents due to the same cause.
Early childhood exposure to bacterial and viral infections and endotoxins (eg, lipopolysaccharide) may normally shift native TH2-cell responses to type 1 helper T (TH1)–cell responses, which suppress TH2 cells and therefore discourage allergic responses. Regulatory T (CD4+CD25+Foxp3+; Treg) cells (which are capable of suppressing TH2-cell responses) and IL-12–secreting dendritic cells (which drive TH1-cell responses) are perhaps also involved. But trends in developed countries toward smaller families with fewer children, cleaner indoor environments, and early use of vaccinations and antibiotics may limit children's exposure to the infectious agents that drive a predominantly TH1-cell response; such trends may explain the increased prevalence of some allergic disorders.
Value of normal flora is being greatly ignored due to use of spoon instead of hand eating, using bottle water for drinking, use of dental paste with antiseptics etc. These habits for many era might affect genetic characters rendering susceptibility to various problems which are not present or less in developing countries.
Hygene hyphotesis is probably the most accepted hypothesis. The immunological systems of humas have evolved for thousands of years with the objective to protect us agaisnt all kind of foreign substances. In the developed countries children are extremely protected from organisms and they are not in contact with other substances of the environment. Beside, the constant use of soap and other products related with the hygene are constantly present in their lives. The immunological system "needs" to be developed during early ages and it founds an environment without action and react with other kind of non-pathological substance.
Changes in genes as a consequence of pollutants and other toxic substances, are im my opinnion other important reason to be taken into account (epigenetics)
It is possible that in developed countries the population above activity Th2-lymphocytes, higher synthesis by cells of the immune system (B-cells- plasma cells, etc.) IgE. This is in respiratory allergies. And it must be clarified: in developed countries over what kind of allergic reaction - contact or respiratory?
Allergic reaction can occur only if the new antigen that could break the barrier of IgA on the mucus membrane or if the mucuc mambrane is disrupted by some injury or inflammatory process.
Several factors including the exposure to neo antigens, IgA deficiency, change in the food habits, diabetes ect may be the predisposing factors. Most of these factors are frequent in the urban areas as well as in the developed countries.
As Vit D deficiency is more common in the urban areas and so is playing in dirt in the child hood is less common in urban areas ( Playing in dirt is good for health was a title of an article published in journal of clinical microbiology).
Putting all this together it is obvious that the incidence of allergies is more
From my understanding, it is because in developing countries, people are more exposed to pathogens from the environment at young as a result of the poorer hygiene, so their body develops a stronger immune system over the years. In contrast, developed countries have a more effective system in promoting and implementing a clean environment for people to live in. Thus, the people are not introduced as much to foreign pathogens, and in turn, their body's immune system is not as developed as those in developing countries.
Why are allergies more common in developed countries than developing countries?
What kind of allergy we say, of the contact (Th1) or respiratory (Th2)?
Let us say at once on the two types of allergic reactions.
Hypothesis.
The answer: in developing countries are often on human roazlichnye allergens (antigens), resulting in a more complete regulation of immune responses by regulatory T cells.
This depends on the type of allergy. For drug-induced allergy, the diagnosis is not staightforward and sometimes difficult to establish. in vitro diagnosis tests are not available in many developing countries and drug-allergies are thus, difficult to confirm.
It is now established that allergy is more common in developed countries than developing countries and similarly it is more in urban than rural area.
1. It should say on the type of allergy - contact or respiratory!
2. The developed countries have a lot of allergens - toxic chemicals. These compounds have strong allergic properties.
3. In developed countries the majority of the population does not face a number of allergens, which are in developing countries. In contact with these allergens among residents of developed countries there is an allergy. In the developing countries are allergic to a number of allergens does not arise, because the frequent contact with them causes desesibilization (or is negative selection of T cells, the removal of T cells with high affinity for the antigen)
4. The higher level of hygiene, culture (people wash their hands, vegetables, fruit, etc.) The more likely an allergy.
Utpal Sengupta, Stanley Browne laboratory, The Leprosy Mission, Delhi
It is true that allergy is more common in developed countries compared to developing and underdeveloped countries. The main reason is being that helminthic infections developing and underdeveloped countries makes the immune system host Th2 biased and therefore Th1 immunity gets suppressed and the host is not rone to allergy, rather the host remains susceptible to Tuberculosis, Leprosy which require Th1 immunity for protection
I wrote about the possible features and functions of Th1-Th2-cells in developed countries and developing countries..
In developing countries the regulatory T cells increase functions of Th2-cells.
But contact allergy related to the function of Th1-cells.
What kind of allergy is it?
My feeling is that it isn't a simple answer of one cause. It does sound, however, like the hygiene hypothesis is a major factor influencing how the immune system develops, and how it is maintained. Is there any data on people who were born and raised in a developing country then moved to a developed country or vice versa? What is the effect of age at the time of moving? It seems like it would be possible to track children from international adoptions. What about animal experiments?
What about animal experiments?
I have not read the articles, which describe such experiments.
I know it is possible to deliver animals aseptically and raise them in a germ free environment. It should be fairly easy to test the hygiene theory by changing the environment at various points, and looking at the immune profile..
Dear Professor Zabrodsky
I still like the ‘Hygiene Hypothesis’
Regards
Ian
Hygiene hypothesis - Yes,.
Changes in polyclonal activation of the immune system with direct or indirect effect on the regulatory NKT cell stimulation might be a crusial mechanism behind. A very good item for further basic research
Utpal Sengupta, Stanley Browne Laboratory, The Leprosy Mission
Yes, I agree that it is a very important area of research to find out the role of regulatory NKT cells.
1) Hygieny hypothesis - Yes (including absense of Helminths)
2) Less vitamin D in urban or low light conditions in Northern areas - Yes
3) Distorted gastrointestinal microflora due to western diet - Yes
4) Visceral obesity incuces chronic low grade inflammation that also predispose and enhance allergic reactions - Yes
5) people are more concious on symptomps and ailments (in old times people in Finland did not know about lactose intolerance. The just had "weak stomach" - nowadays half of population are using lactose free milk products and/or use lactose enzyme capsules. No more "weak stomaches".
Also I feel the occurence of Asthma and COPD is high!!!! pollen, pollution, fumes...
I strongly agree with your observations. In my opinion the commensal gastrointestinal flora play a significant role on the regulation of the immune system, and changing the characteristic of the diet may improve the microbiota and reduces allergic events.
Note that the importance of TLR activation in the immune processes is strategic for development of allergy (see Romagnani S. 2004. Immunology 112: 352-363). The figure 1 of the attached article could be helpful.
Good day Ding:
I would appreciate a copy of this article.
Regards, Nate Stepner
I do not understand what type of hypersensitivity we speak.
On the contact allergy (Th1) or respiratory allergy (Th2)?
A possible factor, alongside with the hygiene hyphotesis, genetic variations, and even lack of information in developing countries concerning allergy, is that depending on the allergy, there might be simply a greater amount of allergens in the environment, since developed countries tend to be more industrialized; people tend to consume more eggs, and so on.
Henrique Borges da Silva!
I wrote about it. But where do the eggs and other products? In developing countries, there are many different allergens, desensitization occurs!
P.F. Zabrodskii,
At first sorry, I really did not see all the comments before I wrote the comment.
Second, desensitization is a fair point that I did not covered. In fact, in developing countries there are other types of allergens, as you pointed out, and desensitization can indeed occur.
However, personally I am not 100% sold on the idea that developed countries have more allergy cases, honestly I think that depending on the type of allergy or depending on the allergen, this simply does not apply. As I said (and other people in this discussion also), lack of information in developing countries can be a major factor in this, accounting for errors in numbers and estimatives. I do believe, although, that urban areas harbor more allergy cases in general.
This Nat Med paper attached shows a positive correlation, in animal models, of repeated RSV infections and asthma susceptibility. RSV infection has likely the same prevalence in countries such as USA and Brazil, Argentina, Thailand (see http://www.who.int/vaccine_research/diseases/ari/en/index2.html); just hyphotetically thinking, in which country the children has more chance to have repeated RSV infections? Another question: do we have more asthma cases in developed world or in developing, third world countries? (see http://www.who.int/respiratory/asthma/en/). That is why I believe that this question does not have a simple, unique answer, but answers that depends on the allergen, on the situation. Moreover I think the question from the beginning is the wrong question to be made. The right question for me is: why there are more allergy cases in urban areas?
Dear Henrique Borges da Silva!
I totally agree with you. You are absolutely correct writing: "I think the question from the beginning is the wrong question to be made. The right question for me is: why there are more allergy cases in urban areas?".
yes, the impact of allergy is less in developing countries b/se of presence of helminth infection. Chemicals from this organisms do have protective effect against allergy occurrence.
I do not understand what type of hypersensitivity we speak.
On the contact allergy (Th1) or respiratory allergy (Th2)?
Respiratopy allergens -----Th2 ----- IL-4, IL-5, IL-6, IL-10 ---- promotiom --- IgE
Contact allergens -----Th1 ----- TNF-beta, IL-2 (Th0), IFN-gamma ---- ingibition---- IgE
It is hard to simplify such a complex question, but it is likely a combination of;
1.) allergies are over-reported in developed countries in which medical care is widely available. It is almost seems fashionable to have some form of "allergy", most of which have been misdiagnosed, often by the patient themselves.
2.) we have eliminated parasites, in particular gut parasites, from populations in the developed world. This could putatively lead to an unbalanced immune system in which Th2 immune responses occur in the absence of any infectious agent..... or so the theory goes!
It would be nice to know about the articles, where it is proved that the allergies are more common in developed countries than developing countries?
this is may be due to, high hygeinic environment in develop countries and so less chance of balanced TH1 and TH2 developemnt, which favours shift of immunity mostly towardsTh1 in childhood. Please you can read more about "Hygeiene hypothesis"...as one solution.
Yes, this is a very complicated matter! The hygiene hypothesis is the most substantiated theory in the scientific community, but I think the evidences are weak and definitive profs have not been acquired. I agree that polyclonal activation of the cells involved in the immune response, especially non-specific, innate immune responses, might be a convincing interpretation.
However I’m persuaded that the environmental pollution, the climate changes and the western life style, play the major role in the allergy epidemic. Scientific studies regarding this topic are to me more persuasive.
this phenomena may be related to reduced parasitic loads in the intestinal tract of individuals in western society: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1906269/
It is now the term "allergy" is used to refer to a type I hypersensitivity reactions. Chemical factors of the environment in developed countries enhance IgE-response and clinical symptoms in the formation of a type I hypersensitivity (increased cytokine production by mast cells, histamine and other mediators).
Maybe this technique will be appropriate...
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0010288
There are many factors contributing more allergic cases in developed countries:
1. The food habit of people living in urban areas in developed country
2. Indoor building environment in urban areas
3. Deficiency of Vitamin D in Western people who are the citizens of developed countries (in general)
4. Some other factors like high atmospheric concentration of grass pollen, affections for pet animals, dry weather conditions etc. favour higher allergic cases.
My understanding is that even in countries such as the UK there can be wide differences in how certain sub-populations develop allergies. I remember reading articles that claimed children living in families with pets such as cats, dogs and other small mammals develop less allergies than those who have no pets. Children brought up on farms show even less liklehood of developing allergies. There is a good review at - http://www.scientificamerican.com/article.cfm?id=fact-or-fiction-pets-protect-kids-against-allergies
It is now the term "allergy" is used to refer to a type I hypersensitivity reactions. Chemical factors of the environment in developed countries enhance IgE-response and clinical symptoms in the formation of a type I hypersensitivity (increased cytokine production by mast cells, histamine and other mediators).
It would be nice to know about the articles, where it is proved that the allergies are more common in developed countries than developing countries?
The answer is obviously multifactorial. For sure, better organised health care system will be more effective in registering incidence of allergy than poorly organised one. Yet some studies have been done comparing the incidence in developed and undeveloped countries and in those studies we cannot say that the difference was due to the health care system organisation since it depended on the study organisation.
Still, challanging the immune system with different allergens seems to decrease the incidence of allergy be those the parasites or other microorganisams. We became too clean and pamper our bodies too much.
I fully agree with Dr. Roglic, and I would highlight the need for well-designed and controlled studies, which take into account all the confounding factors. In fact, there are at least two levels of problems: the proper evaluation of allergy incidence in different countries (and regions within countries), and the identification of infuencing factors.
All the answers are excellent. I would add that the leading cause of immunodeficiency in the world is malnutrition. Much of the 3rd world suffers from this. Good nutrition means a fully functional immune system and part of the price paid for good immunity to infection, is a heightened sensitivity to everything else. This is over simplistic, but partly gets at the issue.
the main cause could be Malnutirtion and pollution. Excessive use of chemicals (pesticides, Urea, DAP, etc etc) in farms, which are entering in our food chain, and if you try to use excessive cleaning agents (cosmetics) on your body, this will also start eliminating your skin microbiota which in a way could lead to skin to be exposed to air pollutants, etc etc and finally to Allergy.
I agree immunity has to play a very crucial role, but one should also consider that Immunity acts from inside where as allergens mostly acts on first line of defense, like skin, or mucosal layers. which are mostly deteriorated by not having proper diet (that is from inside the body) and excessive use of cosmetics and chemicals (that is eliminating good commensal microbiota).
thanks
@ Dr. Dagur....very good point!
One can add that hypersensitivity involving IgE would involve part of the "inside" immune response too...
Dr. David Wagner! Probably the lack of food intake in some way can influence the formation of allergies. We consider the first type hypersensitivity. Lack of nutrition can reduce the synthesis of IgE. In this case, the probability of allergy (respiratory, immediate type) decreases. (?)
Dr. Pradeep Dagur ! It is now the term "allergy" is used to refer to a type I hypersensitivity reactions. Chemical factors of the environment in developed countries enhance IgE-response and clinical symptoms in the formation of a type I hypersensitivity (increased cytokine production by mast cells, histamine and other mediators).
Dr. David Wagner! It is now the term "allergy" is used to refer to a type I hypersensitivity reactions. Chemical factors of the environment in developed countries enhance IgE-response and clinical symptoms in the formation of a type I hypersensitivity (increased cytokine production by mast cells, histamine and other mediators) [I. Roitt, 2000].
I already wrote about the hygiene hypothesis. This hypothesis is no denying.
It is now well established that allergy is genetically determined and environmentally triggered. The triggereing factors vary in developed and developing countries and are important geographical triggers, I agree that the recent understanding of immunological disease at molecular level has created good diagnostic facilities at both invivo and invitro levels. Even in developing countries I am sure hygiene hypothesis is one of the factors for reduced prevalence of allergy I am from a developing country like India and here studies do indicate that allergy is less prevalent in rural areas than in urban setup. Further a good example of different food habis and processing method plays very important role. In developed countries like USA and Europe Pea Nut allergy leading to anaphylaxix is common but in developing countries where it id consumed in tones does not cause that much allergy.
A B SINGH
So, statement: "It is now established that allergy is more common in developed countries than developing countries and similarly it is more in urban than rural area" -
not conclusive.
One reason for urban vs. rural in developing countries is the incidence of parasite infection. It has been shown that burden of helminths for example is inversely correlated with sensitisation.
Probably, overstimulation of immune system by burden of pathogens, parasites and protozoans etc might have produce other classes of Ig or allergen non-specific IgE occupying or blocking surfaces of mast cells/eosinophils. This theoretically will prevent crossing of IgEs.
Due to protein deficiency (% of protein deficiency is high in developing countries), so developing countries not get allergies than developed country... (mostly protein only responsible for allergies).. If i'm wrong please correct me..
I agree with Dr. Ganiyu Arinola .
Activation of mast cells and basophils requires specific IgE molecules that are bound to adjacent Fc receptors that are cross linked by a specific allergen. Helminths have a large number of different epitopes or antigenic determinants each of which is capable of generating specific IgE molecules.
To activate the mast cell or basophil the adjacent receptors must have identical IgE molecules with the same specificity for the allergen. Since a large number of IgE molecules with specificities to different helminth epitopes are present - it is very unlikely that two adjacent Fc receptors will be occupied with two identical IgE molecules with the same specificity for an allergen. If this is the case cross linking will not occur and the mast cell or basophil will not be activated
Several reasons at developing country
Hygiene theory, under diagnosed (treated as if it is an infections and less qualified allergist and no registry system)
Earl (or anyone else willing to answer),
It is understandable that there might be several IgEs with different specificity at the Fab end, the Fc receptors on mast cells and basophils are able to bind any IgE regardless of specificity. If there is an abundance of IgE specific for a single antigen which is widely dispersed on the helmith, I suppose the cross-linking would be hampered. If, however, there were IgEs present, each with a different specificity, you could still get cross-linking. I can imagine helminths and other microbes evolving to spread out surface antigens to avoid attack by a single IgE clone. In the presence of helminths the various IgEs are bound and eventually able to destroy the target. In the absence of helminths the body is seeing less diversity, and it is able to then easily produce a hypersensitive response to the less complicated antigens present in the environment. Any thoughts?
Well, I have an additional suggestion. It's not only allergy prevalences that are high but also autoimmune diseases. This suggests that something is changing our immune system. It could very well be our microbiota and its interaction with the immune system. And then there may be several reasons for the effects on the microbiota. With regard to allergy, we see many children suffering from this already at a young age. 25 % of Danish children under 7 develop atopic eczema (Harpsøe et al 2013). We and our mothers are exposed to hundreds of different chemicals, which are measurable in blood. I think many of these chemicals (or perhaps the cocktail of these) very well could exert negative effects on our immune system. What mothers are exposed to may affect the developing fetus also epigenetically and thus cause transgenerational effects (several studies by Fedulov). This has been observed in animal models with pollutants . Also, the inheritance of asthma is stronger from the mother than the father (Lim et al 2010). Different pollutants are under suspicion of being endocrine disruptors. Phthtalates have been suggested as being "immune" disruptors, but the evidence is not convincing. PFCs are connected with impaired vaccine responses in children (Grandjean et al 2012).
Allergologists are less interested in this subject than toxicologists, what about you?
I agree with the opinion of Dr. Jitka Hansen.
Typically, xenobiotics inhibit to varying degrees nonspecific resistance of the organism, both humoral and cellular immune responses. At the same time, there may be various hypersensitivity reaction (1 - 5 of types where certain immune system responses increased). These reactions, as well as suppression of the immune response may be a manifestation of immunotoxicity xenobiotics. Variants, when one of the components providing immune homeostasis, increased by suppressing others. Basically, contact and xenobiotic cause respiratory allergic reaction. Contact allergens activate Th1-lymphocytes, which, by means of cytokines (IL-2, IFN-γ, TNF-β, etc.) recruit macrophages and monocytes to implement type IV hypersensitivity reactions (delayed type hypersensitivity). In the reaction involved Langerhans cells and keratinocytes. Furthermore, contact allergens, producing IL-2, IFN-γ and TNF-β, inhibit the synthesis IgE. Respiratory allergies, affecting Th2-lymphocytes activate their production of IL-4, IL-5, IL-6, IL-10, promoting synthesis plasmocytes IgE. These immunoglobulins, which are localized on mast cells, interact with antigens (allergens) to cause respiratory allergic (hypersensitivity reaction type I) (Kimber I., 1996). Pharmacological agents may cause drug intolerance caused by an allergic reaction of type I, II, III, connecting the various components of the body (in particular blood cells) and developing in grade of hapten antigen. The interaction of blood cells with cytotoxic antibodies produced and sold allergic reaction type II. Medicaments binding to serum proteins can cause reactions III, due to the formation of immune complexes. Reactions of type V (autosensibilization due antibodies) available by reacting antibodies (xenobiotic) with key components of the cell surface (e.g., a hormone receptor, which leads to cell activation) (Zabrodskii P.F., 2002, 2007; Descotes J., 2004]).
It is important to remember that breakdown of allergy prevalence is not based purely on developed/developing countries but also on socioeconomic status within countries. In addition, there are differences between allergies seen in the Western world and Asia, as excellently outlined in the article here http://www.expert-reviews.com/doi/full/10.1586/eci.09.82?prevSearch=allfield%253A%2528Allergies%2Bin%2BAsia%255C%253A%2Bdifferences%2529&searchHistoryKey=
Expert Rev Clin Immunol. 2010 Mar;6(2):279-89.
Allergies in Asia: differences in prevalence and management compared with western populations.
Gerez IF, Lee BW, van Bever HP, Shek LP.
Source
National University Health System, Department of Pediatrics, Singapore.
Abstract
There is wide variability in the epidemiology and management of childhood asthma and related atopic diseases globally. Urbanized, affluent Western countries tend to have a higher prevalence of these diseases compared with Asian nations. However, recent studies have shown that the prevalence in Asia is increasing, although the rate of increase has slowed in the more developed Asian cities. Some possible causes for these differences are socioeconomic status, degree of urbanization, rates of infection, healthcare practices and genetic factors. Importantly, there are significant differences in the way asthma and allergic diseases are managed within Asia. This is of great concern because of the health implications, as these diseases are some of the most common chronic conditions that affect both adults and children. This review compares the differences in prevalence and management between Asia and the West, and discusses some of the possible reasons behind these variations.
PMID: 20402390 [PubMed - indexed for MEDLINE]
http://www.expert-reviews.com/doi/full/10.1586/eci.09.82?prevSearch=allfield%253A%2528Allergies%2Bin%2BAsia%255C%253A%2Bdifferences%2529&searchHistoryKey=
Expert Rev Clin Immunol. 2010 Mar;6(2):279-89.
Allergies in Asia: differences in prevalence and management compared with western populations.
Gerez IF, Lee BW, van Bever HP, Shek LP.
Source
National University Health System, Department of Pediatrics, Singapore.
Abstract
In addition to explanations of Dr. Jitka and Dr. Zabrodskii whose approach to explain the question is more technological and scientific, I feel it is the body's reaction or response to the changed environment. More than an explanation for the allergy on rising trend in developed countries, my feeling is the way in which and the speed with which the environment is modified with more and more of synthetic materials, chemicals in the form of drugs, pesticides, exhausts, industrialization. In addition to our exposure to all these inputs in the environment, we are constantly exposed to man made amenities, which might be silently disturbing the immune system??
I dont have adequate scientific evidences to make my argument strong, but we have to think sometimes "out of the box" to realize the realities.
In the laboratory, we always make one to one equation by studying one molecule or one property of an isolated cell to implicate some factor/molecule as a causative factor for what is being observed.
We also have to remember that man is a complex eukaryotic organism like any other higher vertebrate, built with enormous number and variety of molecules whose mutual interaction and mutual dependence, chemical reactions and the physical properties govern the successful existence assisted by normal physiological activities of all organs. Man as a complex organism would react to changes in the environment.......some reactions are visible while other changes are not manifested; but would influence for sure the physiology.
In this context, I wish to recall Gerald Rubin "Biological organisms don't work just one gene at a time. The genes interact with each other in very complicated pathways and net works. We have tended to over simplify biology to fit what we could work on in the lab. We have had successes."
I agree with Adeeb Rahman, along with hygiene hypothesis, there is very much influence of living standard in both developed and undeveloped country. Other aspect is the exposure to microbes and parasites.
Yes, you are right Dr. Liadaki. Innumerable number of factors might influence the threshold of "sensitization" of immune system in such a way that the plasma cells make an isotype switch, so that instead of producing IgG they start producing IgE.
If we just browse the recent reviews on immunology, we find many new findings......new roles and mechanisms of their functioning. The explanations hitherto that were not given are being ventured. Nature's working is a mystery and that has to be unraveled with scientific temper and pursuit
Http://www.bbc.com/future/story/20130422-feeling-ill-swallow-a-parasite
Antibiotic administration in the very young age modifies the intestinal flora and supports the appearance of food allergies
Dear Nicole, is it also the reason why antibiotics are not advised for pregnant women especially after 4th or 5th month of pregnancy??
I think is might be due tomtypes of food ,drinks anf life style as well due to environmental pollution which more heavy in developed countries .All these factors might lead to emergence of new allergens more the under developed coutries who still live on fresh and natural foods and drinks and the obesity is lower in these countries which would be anothe factor impacting allergy .there are another possible causes related to the subject.
In addition to above mentioned theories, genetic and environmental factors play major roles in more allergy incidences in developed countries.
The allergens are more due to the damage in the environment. Poor standards of unhygienic living etc. lalitha kabilan
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