Allergy Shari

8/6/2019 Allergy Shari

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ALLERGY

Submitted by:

Shari Mitra

Class XI B


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INDEX

1. INTRODUCTION ..........................pg 3

2. CERTIFICATE ..........................pg 4

3. ACKNOWLEDGEMENT ..........................pg 5

4. WHAT IS ALLERGY? ...........................pg 6

5. CAUSES ............................pg 7

6. ALLERGENS .............................pg 8

7. SIGNS AND SYMPTOMS .......................pg 10

8. IMMUNE SYSTEM ........................pg 12

9. LAB INVESTIGATION ........................pg 15

10. TREATMENT .............................pg 1811. STATISTICAL DATA .............................pg 20

12. SUMMARY ............................pg 23

13. CONCLUSION ..............................pg 24

14.REFERENCE ............................pg 25


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Introduction

Allergies are quite a common affliction most of us suffer in

our day-to-day life. Thus, as a subject it is relevant as well as

interesting to know the symptoms, causes and cure.

While studying some reference books on Biology, I came

across this subject and felt interested to study this subject in

detail.

This study is the outcome of my efforts in gathering relevant

excerpts, exhibits and diagrams from various sources and

putting it together with my understanding on the subject.

I have tried to present the subject in a simple manner.

I have enjoyed doing this project. It has also added to my

knowledge and interest in Biology.


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CERTIFICATE

This is to certify that Shari Mitra of Class XI B

has carried out this study as a part of her

Biology practical for the 2010-11 session.

Date: Signature:


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ACKNOWLEDGEMENTS

I would like to thank our biology teacher, Dr Ms Shylaja Pillai, for

teaching and guiding me.

I would also like to thank our school principal for providing me

this opportunity.

I am deeply indebted to Dr Ms Kavita Merchant for providing

valuable tips and information for this project.

Lastly I would like to thank my parents and friends for their love

and support.


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WHAT IS ALLERGY?

Allergy is a hypersensitive disorder of the immune system. It

refers to an exaggerated reaction by our immune system inresponse to bodily contact with certain foreign substances. It is

exaggerated because these foreign substances are usually seen by

the body as harmless and no response occurs in non- allergic

people. Allergic people's bodies recognize the foreign substance

and one part of the immune system is turned on.

Allergy-producing substances are called "allergens." When an

allergen comes in contact with the body, it causes the immune

system to develop an allergic reaction in persons who are allergic

to it .These reactions are acquired, predictable, and rapid. When

you inappropriately react to allergens that are normally harmless

to other people, you are having an allergic reaction and can be

referred to as allergic or atopic. Therefore, people who are prone

to allergies are said to be allergic or "atopic."

Strictly, allergy is one of four forms of hypersensitivity and is

called type I(or immediate) hypersensitivity. It is characterized by

excessive activation of certain white blood cells called mast

cells and basophils by a type of antibody known as IgE, resulting

in an extreme inflammatory response.


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CAUSES

Risk factors for allergy can be placed in two general categories,

namely host and environmental factors. Host factorsinclude heredity, gender, race, and age, with heredity being by far

the most significant.

Our own risk of developing allergies is related to our parents'

allergy history. If neither parent is allergic, the chance that we will

have allergies is about 15%. If one parent is allergic, our risk

increases to 30% and if both are allergic, our risk is greater than

60% . However, there have been recent increases in the incidence

of allergic disorders that cannot be explained by genetic factors

alone.

Four major environmental candidates are alterations in exposure

to infectious diseases during early childhood,

environmental pollution, allergen levels, and dietary changes.

It is clear that we must have a genetic tendency and be exposed to

an allergen in order to develop an allergy. Additionally, the moreintense and repetitive the exposure to an allergen and the earlier

in life it occurs, the more likely it is that an allergy will develop.


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ALLERGENS

Allergens are substances that are foreign to the body and can

cause an allergic reaction in certain people. These can also becategorised as indoor, seasonal, food and miscellaneous allergens,

shown as below,

Indoor Allergens

DUST MITESMOLDS

PET DANDER

COCKROACH

Seasonal Allergens

POLLENS

GRASS

WEEDS

POISON IVY

Food Allergens

PEANUT

MILK

CHOCOLATES


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SPICES

SEEDS

SHELL FISH

NUTS

WHEAT

Miscellaneous

NICKEL COINS

LATEX

CANDELS

COSMETICS

WALL PAINT

ANTIBIOTICS

ASPIRIN

INSECT STINGS

PERFUME

DETERGENT


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ALLERGIES, AFFECTED ORGANS

& SYMPTOMS

Affected organ Symptom

Nose

swelling of the nasal mucosa (allergic rhinitis),

running nose, sneezing, stuffy nose, nasal

itching

Sinuses allergic sinusitis

Eyesredness and itching of the conjunctiva (allergic

conjunctivitis)

Airways

sneezing,

coughing, bronchoconstriction, wheezing and

dyspnea, sometimes outright attacks of asthma,

in severe cases the airway constricts due to

swelling known as laryngeal oedema

Ears

feeling of fullness, possibly pain, and impaired

hearing due to the lack of eustachian

tube drainage, itchy ears

Skinrashes, such as eczema and hives (urticaria),

itchiness


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MULTIPLE ORGANAFFLICTIONS

Insect stings, antibiotics, and certain medicines produce a systemic

allergic response that is also called anaphylaxis; multiple organ

systems can be affected, including the digestive system,

the respiratory system, and the circulatory system.

Depending on the rate of severity, it can cause cutaneous reactions,

bronchoconstriction, oedema, hypotension, coma, and even death.

Skin involvement may include generalized hives, itchiness, flushing,

and swelling of the lips, tongue or throat.

Respiratory symptoms may include shortness of breath,

wheezes and low oxygen.

Gastrointestinal symptoms may include crampy abdominal pain,

diarrhea, and vomiting.

Cardiovascular symptoms are due to the presence of histaminereleasing cells in the heart coronary artery, thus spasm may occur

with subsequent myocardial infarction or dysrhythmia.

Nervous system symptoms are due to drop in blood pressure, which

may result in a feeling of lightheadedness and loss of consciousness.

There may be a loss of bladder control and muscle tone, and a feeling

of anxiety and "impending doom".

Gastrointestinal

tractabdominal pain, bloating, vomiting, diarrohea


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RESPONSE OF IMMUNE SYSTEM TO

ALLERGENS

The immune system is the body's organized defence mechanismagainst foreign invaders, particularly infections. Its job is to

recognize and react to these foreign substances, which are called

antigens. Antigens are substances that are capable of causing the

production of antibodies. Antigens may or may not lead to an

allergic reaction. Allergens are certain antigens that cause an

allergic reaction and the production of IgE.

The aim of the immune system is to mobilize its forces at the siteof invasion and destroy the enemy. One of the ways it does this is

to create protective proteins called antibodies that are specifically

targeted against particular foreign substances. These antibodies,

or immunoglobulins (IgG, IgM, IgA, IgD), are protective and help

destroy a foreign particle by attaching to its surface, thereby

making it easier for other immune cells to destroy it.(IL-4).

The allergic person however, develops a specific type of antibody

called immunoglobulin E, or IgE, in response to certain normally

harmless foreign substances. Immunoglobulins are a group of

protein molecules that act as antibodies. There are five different

types; IgA, IgM, IgG, IgD, and IgE. IgE is the allergy antibody.

In the early stages of allergy, a type I hypersensitivity reaction

against an allergen, encountered for the first time, causes a

response in a type of immune cell called a TH2 lymphocyte, which

belongs to a subset of T cells that produce a cytokine called

interleukin-4 (IL-4).


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These TH2 cells interact with other lymphocytes called B cells,

whose role is production of antibodies. Coupled with signals

provided by IL-4, this interaction stimulates the B cell to begin

production of a large amount of a particular type of antibody

known as IgE.

Secreted IgE circulates in the blood and binds to an IgE-specific

receptor (a kind of Fc receptor) on the surface of other kinds of

immune cells called mastcells and basophils, which are both

involved in the acute inflammatory response. The IgE-coated

cells, at this stage are sensitized to the allergen.

If later exposure to the same allergen occurs, the allergen can

bind to the IgE molecules held on the surface of the mast cells or

basophils. Cross-linking of the IgE and Fc receptors occurs when

more than one IgE-receptor complex interacts with the same

allergenic molecule, and activates the sensitized cell.

Activated mast cells and basophils undergo a process

called degranulation, during which they release histamine and

other inflammatory chemical mediators from their granules into

the surrounding tissue causing several systemic effects, such

as vasodilation, mucous secretion, nerve stimulation and smooth

muscle contraction. This results in rhinorrhea, itchiness,

dyspnea, and anaphylaxis. Depending on the individual,

allergen, and mode of introduction, the symptoms can be system-

wide (classical anaphylaxis), or localized to particular body

systems; asthma is localized to the respiratory system and

eczema is localized to the dermis.

After the chemical mediators of the acute response subside, late

phase responses can often occur.


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This is due to the migration of other leukocytes such

as neutrophils, lymphocytes, eosinophils and macrophages to the

initial site. The reaction is usually seen 224 hours after the

original reaction. Cytokines from mast cells may also play a role in

the persistence of long-term effects. Late phase responses seen

in asthma are slightly different from those seen in other allergic

responses, although they are still caused by release of mediators

from eosinophils, and are still dependent on activity of TH2 cells.


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LAB INVESTIGATION / DIAGONOSIS

Skin testing

Pricktest

It is also known as "puncture testing" and "prick testing" due to

the series of tiny puncture or pricks made into the patient's skin.

Small amounts of suspected allergens and/or their extracts

(pollen, grass, mite proteins, peanut extract, etc.) are introduced

to sites on the skin marked with pen or dye.

A small plastic or metal device is used to puncture or prick the

skin. Sometimes, the allergens are injected "intradermally" into

the patient's skin, with a needle and syringe. Common areas for

testing include the inside forearm and the back. If the patient is

allergic to the substance, then a visible inflammatory reaction will

usually occur within 30 minutes.

This response will range from slight reddening of the skin to a

full-blown hive (called "wheal and flare") in more sensitive

patients. Interpretation of the results of the skin prick test isnormally done by allergists on a scale of severity, with +/-

meaning borderline reactivity, and 4+ being a large reaction.

To ensure that the skin is reacting in the way it is supposed to, all

skin allergy tests are also performed with proven allergens like

histamine or glycerine . The majority of people do react to

histamine or glycerin. Ifthe skin does not react to these

allergens then it mostlikely will not react to the otherallergens. These results are interpreted as falsely negative.


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Patch test

The patch test simply uses a large patch which has different

allergens on it. The patch is applied onto the skin, usually on the

back. The allergens on the patch include latex, medications,

preservatives, hair dyes, fragrances, resins and various metals.When a patch is applied the subject should avoid bathing or

exercise for at least 48 hours.

Skin endpointtitration

Skin end point titration (SET) uses intradermal injection of

allergens at increasing concentrations to measure allergic

response.

To prevent a severe allergic reaction, the test is started with avery dilute solution. After 10 minutes, the injection site is

measured to look for growth of wheal, a small swelling of the skin.

Two millimeters of growth in 10 minutes is considered positive. If

2 mm of growth is noted, then a second injection at a higher

concentration is given to confirm the response. The end point is

the concentration of antigen that causes an increase in the size of

the wheal followed by confirmatory whealing. If the wheal grows

larger than 13 mm, then no further injection are given since this isconsidered a major reaction.

Blood Testing

This kind of testing measures a "total IgE level" - an estimate of

IgE contained within the patient's serum. This can be determined

through the use of radiometric and colormetric immunoassays.

Radiometric assays include the RAST test method, which uses

IgE-binding (anti-IgE) antibodies labeled with radioactive

isotopes for quantifying the levels of IgE antibody in the blood.

Other newer methods use colorimetric or fluorometric technology

in the place of radioactive isotopes.


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An absolute eosinophil count is a blood test that measures the

number of white blood cells called eosinophils. Eosinophils

become active when you have certain allergic diseases.

Elimination/Challenge tests

This testing method is utilized most often with foods or

medicines. A patient with a particular suspected allergen is

instructed to modify his/her diet to totally avoid that allergen for

determined period of time. If the patient experiences significant

improvement, he/she may then be challenged by reintroducing

the allergen to see if symptoms can be reproduced.

Challenge testing is when small amounts of a suspected allergen

are introduced to the body orally, through inhalation, or other

routes.


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TREATMENT

Treatments for allergies include allergen avoidance, use of anti-

histamines, steroids or other oral medications, immunotherapyto desensitize the response to allergen, and targeted therapy.

A few common methods of treating allergies:

For air borne allergens - medications like nasal sprays,

decongestants and antihistamines have known to be

effective. Also, eye drops can be used in case of itchiness of

the eye.

For ingested Allergens - in case of a resultant skin reaction

use easily available skin ointments which can be procured

over the counter. In case of wheezing, choking etc.

antihistamines might come in hand. If ingested material is

some sort of food then avoiding it altogether might help.

Allergy to insect bites or certain types of drug - Injections of

Epinephrine (adrenaline) are known to be helpful

Traditional treatment and management of allergies consist simply

of avoiding the allergen in question or otherwise reducing

exposure.

For instance, people with cat allergies are encouraged to avoid

them. Avoidance is always the best treatmentfor allergiesregardless ofwhich allergens are the triggers.

However, while avoidance of allergens may reduce symptoms and

avoid life-threatening anaphylaxis, it is difficult to achieve for

those with pollen or similar air-borne allergies.


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Nonetheless, strict avoidance of allergens is still considered a

useful treatment method, and is often used in managing food

allergies.

PHARMACOTHERAPY

Several antagonistic drugs are used to block the action of allergic

mediators, or to prevent activation of cells and degranulation

processes. These include antihistamines,

glucocorticoids,epinephrine (adrenaline), theophylline and

cromolyn sodium. Anti-leukotrienes, such as Montelukast

(Singulair) or Zafirlukast (Accolate), are FDA approved for

treatment of allergic diseases.[citation needed] Anti-cholinergics,decongestants, mast cell stabilizers, and other compounds

thought to impair eosinophil chemotaxis, are also commonly

used. These drugs help to alleviate the symptoms of allergy, and

are imperative in the recovery of acute anaphylaxis, but play little

role in chronic treatment of allergic disorders.

Immunotherapy

Desensitization or hyposensitization is a treatment in which the

patient is gradually vaccinated with progressively larger doses of

the allergen in question. This can either reduce the severity or

eliminate hypersensitivity altogether. It relies on the progressive

skewing of IgG antibody production, to block excessive IgE

production seen in atopys. In a sense, the person builds up

immunity to increasing amounts of the allergen in question.

Studies have demonstrated the long-term efficacy and the

preventive effect of immunotherapy in reducing the development

of new allergy.

A second form of immunotherapy involves the intravenous

injection of monoclonal anti-IgE antibodies. These bind to free


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and B-cell associated IgE; signalling their destruction. They do not

bind to IgE already bound to the Fc receptor on basophils and

mast cells, as this would stimulate the allergic inflammatory

response.

A third type, Sublingual immunotherapy, is an orally-

administered therapy which takes advantage of oral immune

tolerance to non-pathogenic antigens such as foods and resident

bacteria.

ALERNATIVE TREATMENT

A number of allergy treatments are described by its practitioners,

particularly naturopathic, herbal medicine, homeopathy,

traditional Chinese medicine, and applied kinesiology.


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STATISTICAL DATA

One in every 10 Indian children suffers from allergies and asthma,

yet the condition is often not acknowledged because medical

schools do not recognise the treatment of allergies as a legitimate

specialisation. As a result, there are only a few trained experts

who can diagnose the condition.

There is also evidence of an important link between allergic

diseases and air pollution outdoors and indoors. In cities and

especially in city centres, where air is polluted the most thenumber of children with asthma is increasing the most.

The consequences for children are particularly harmful. A studyon the prevalence of allergic rhinitis in Southeast Asia found that

allergies impacted the quality of life of up to 80 per cent of

children in the age group of 6 to 11 years.

Conditions like allergic rhinitis affected their sleep pattern, their

learning performance, and their ability to play games and

participate in leisure activities. The condition get aggravated

when pollution levels rise in the city atmospheric pollutants like

sulphur dioxide, or nitrogen oxides or suspended particulatematter (SPM) which are not allergens but they enhance and

amplify the severity of the disease in people who are already

sensitive to a variety of allergens such as dust mites, animal

dander, pollen, fungi, moulds and even cockroaches.

Insects, particularly mosquitoes, cockroaches and dust mites, are

to blame for nearly 50% of the allergies in India. And food

especially peanuts, chocolates and legumes is the other big

culprit.Study also shows that allergies can be gender-sensitive. Teenage

boys are less likely to be sniffling through college as they outgrow

their allergies by adolescence while girls may continue to suffer in

these years.


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In the US and Europe, pollen from flowering plants is a common

trigger for allergies, accounting for 20% of all cases. Not so in

India where a mere 8.61% of patients studied showed wheezing

or blocked noses because of pollen. Asthma and rhinitis

predictably formed the major chunk of all allergies in India.

Interestingly, food allergies are more common here than among

westerners. Take, for instance, the allergy to rice which was only

reported from Japan till now but which has showed up among

Indians. Or take chocolates, the second most common food

allergen in the study. While the western palate is most sensitive to

milk, egg, meat and wheat, Indians are likely to react to peanuts,

chocolates, and legumes (dal).


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CONCLUSION

Allergies are a serious public health problem in many countries.

In the past three decades the number of allergic diseases

(including asthma) has increased sharply and it seems that the

upward trend will continue in the future. The number of sick

people has increased both among children and adults and in all

social classes. According to the World Health Organization, 25%

to 40% of people in industrialized countries have allergic rhinitis

and 20% have allergic asthma, which poses a serious threat to

public health.

Lack of information about the condition leads most people to deal

with the problem symptomatically.People need to first recognise

what triggers off their allergies.

Even parents treat children for such allergies only up to the point

where they get some relief without understanding that it is a

condition that ought to be taken seriously and treated.

Avoidance is always the best treatment for allergies regardless of

which allergens are the triggers.

Many doctors admit that there is no cure for many allergies,

however the new generation of drugs allow people to manage

allergic reactions and lead a normal life.


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REFERENCE

WikipediaMedicineNet.com

E-medicine.comPaediatric Help & Future Science GroupMerchant Homeopathic Clinic, Anandpharmabiz.comHindustan Times article dated 22 July, 2008The Hindu article dated 5 Dec, 2004

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