Allergies
Allergy is the Hypersensitiveness of a person to some foreign substance coming in contact with or entering the body.
Allergens = The substance that cause allergic reaction are called allergens. The common allergens are dust, pollen, mould, spores, fabrics , lipsticks, nail paints, feathers, fur, plants, bacteria, foods , heat, cold sunlight.
Symptoms =
The Symptoms that result from an allergy May be of different kinds but mostly it affects the skin and mucous membrane.
Symptoms of allergic reaction include sneezing, watery eyes , running nose and difficulty in breathing.
Cause :-
Allergy involves mainly IgE antibodies and chemicals like histamine and serotonin from mast cells and basophils.
The allergic tendency is genetically passed from parent to child and is characterised by the presence of large quantities of Ig E antibodies in the blood
These antibodies are called Sensitizing antibodies to distinguish them from the more common IgG antibodies.
First exposure to antigen causes primary immune response , but it doesn’t cause allergy .
When an allergen enters the body second time , it causes second immune response reaction and a subsequent allergic reactions occurs. It causes marked dilation of all the peripheral blood vessels and the capillaries become highly permeable so that large amounts of fluid leak out from the tissue. The blood pressure decrease drastically.
Some firm of allergy are mentioned below
(I) Hay Fever
It is a form of allergy due to Pollen of grasses, trees and other plants. It is characterised by inflammation of the membrane lining the nose and sometimes of the conjunctiva. The Symptoms of Sneezing, running or blocked nose and watering eye due to histamine releases often respond to the treatment with antihistamines.
(ii) Asthma :
The tissue surrounding the bronchioles of the lungs swell up and compress the bronchioles. Hence there is difficulty in breathing. Administration of antihistamines has little effect on the course of asthma because histamine does not appear tot be major factor causing the asthmatic reaction.
Treatment is with bronchodilators with or without corticosteroid, usually administered via aerosols or dry powder inhalers.
Avoidance of known allergens especially the house dust mite, allergens arising from domestic pets and food additives will help to reduce the frequency of attacks as will discouragement of smoking.
(iii) Anaphylaxis ( Anaphylactic shocks).
It is an allergic reaction involving all the tissue of the body occurs in a few minutes after the injection of antigen such as penicillin.Such a reaction is very serious. Histamine released from ruptured mast cells causes marked dilation of all the arteries so that a large amount of fluid is passed from the blood to the tissue and the tissue and there is a drastic fall in blood pressure. The affected person May become unconscious and the individual May die within a short time.
The use of drugs as antihistamines, adrenaline and steroids quickly reduce the symptoms of allergy.
Autoimmunity
The unique property of the immune system is that it always destroys the foreign proteins but never attacks the body own proteins.
Definition
If the immune system fails to recognize ‘Self’ From ‘noself’ and starts destroying the body’s own proteins, this leads to some malfunctions which are called autoimmune disease. This immunity is known as autoimmunity.
Cause :-
Autoimmunity is caused due to following,
Genetic Factors.
Some individual are genetically more susceptible to developing autoimmune diseases than others. This mostly happens when certain genes start showing abnormalities. These genes could be those of antibodies, T cells receptors and MHC genes (major histocompatibility complex genes). Autoimmune disorders occur more in women than in men. Autoimmunity seems to run un some families.
Enviromental Factors :
Environmental also plays some role in the induction of autoimmune diseases. Besides autoimmune disease can be manifested because of certain part of the immune system, which get elevated in almost all autoimmune disorder.
Increased helper T cell and decreased suppressor T cell functions have been suggested as causes of autoimmunity. Autoimmune disease are caused by self reacting antibodies.
Example — Some Important examples of autoimmune diseases are given below
- Addision’s Disease
- Diabetes Mellitus (type 1)
- Graves’ Disease
- Autoimmune Hemolytic anaemia
- Hashimoto’s Thyroiditis
- Multiple Sclerosis
- Myasthenia Gravis
- Rheumatic fever
- Rheumatoid Arthritis
- Systemic lupus erythematosus (SLE)
Possible Treatments
To control different types of autoimmune diseases , continuous attempts are being made to develop newer and advanced treatment options
(I) Use of Immunosupressants = Immunosuppressive drugs (eg — corticosteriods, azathioprine and Cyclophosphamide) are often given to reduce the severity of the autoimmune disorders . but as this treatment suppress the overall immune response , the patients are at great risk of having cancer and other diseases.
(ii) Plasmapheresis = In this line of treatment the plasma is first separated from the patient’s blood by centrifugation . After removing the reactive autoantibodies from plasma , the blood is transfused back to the patient .
(iii) T Cell Vaccination = Vaccination using T cell can be effective means of treating autoimmune disease.
(iv) Use of Monoclonal Antibodies = Monoclonal antibodies have been successful used in the treatment of autoimmune diseases.
(v) Use of Stem cells — Adult hematopoietic stem cell transplantation can be done.
Immunodeficiency Disease
Immunodeficiency disease are conditions where the defence mechanisms of the body are weekend , leading to repeated microbial infections.
Types —
Immunodeficiency disease May be primary or secondary
(I) primary Immunodeficiency Disease —
These disease exist from the birth. A person May be without B cells or T cells or both from the birth.
Example — Severe Combined immunodeficiency Disease (SCID)
(ii) Secondary Immunodeficiency Disease
A variety of factors such as malnutrition, infections , metabolic disorders , malignancy and cytotoxic drugs May lead to defects in specific and non specific immunity.
Thus Secondary immunodeficiency disease are more common than primary deficiency disease .
Examples — AIDS and Hodgkin’s disease (a malignant disease of lymphatic tissue — a form of Lymphoma)
SCID — Severe Combined Immunodeficiency Disease
The person who is suffering from SCID lacks both B cell and T Cell from birth. It is a serious genetic disease in which the person is highly susceptible to infection.
AIDS — Acquired Immune Deficiency Syndrome
AIDS is a disorder of cell mediated immune system of the body. There is a reduction in the number of helper T cells which stimulate antibody production by B cells. This results in the loss of natural defence against viral infection.
Discovery
AIDS was first notice in USA among homosapiens. AIDS virus was discovered by Luck Montagnier and Colleagues at the institute pasteur, paris in 1983. It was named lymphadenopathy associated virus (LAV)
Pathogen (causative Agent )
The virus was identified and named by Americans as HCLV lll (human cell leukemia virus. lll) but stated earlier the name of. The virus wad changed to HIV (human immunodeficiency Virus)
Transmission
Virus of AIDS is transmitted via blood and semen
- Transfusion of infected blood or blood products
- Use of Contaminated needles and Syringes to inject drugs and vaccine
- Use of Contaminated razors
- Use of Contaminated needles for boring pinnae
- Sexual intercourse with an infected partners without a condom
- From infected mother to child through placenta
- Artificial insemination
- Organ Transplant
Incubation Period
The incubation period of AIDS ranges between 6 months to 10 years
Symptoms
The symptoms of HIV infection include fever, lethargy , pharyngitis, nausea , Headache, rashes etc
Diagnosis
- AIDS can be diagnosed by ELISA test and Western blotting test.
- Western blotting test is employed for Confirmation of ELISA positive cases.
Prevention : No vaccine has been prepared so far against AIDS virus. The following steps May help in preventing AIDS
- People should be educated about AIDS. Every year , December 1 is recalled as the World AIDS Day. It is one of the method to educate the people about AIDS.
- Blood test must be done in blood donors, donors of semen, donors of organs (kidne , lung, liver ) , patients undergoing haemodialysis and pregnant women.
- Disposable needle and syringes should be used. Used needles and syringes must be destroyed
- In sexual relationship one should be monogamous
- Dentist should use sterilized equipment
- Avoid tattoos, ear and nose piercing from unqualified people
- Avoid use of common blades in barber’s shops.
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