What is Allergy

What is Allergy

Most of us encounter conditions such as running nose, swelling and reddening of the nose, eyes, Continuous sneeze on exposure to dust. This is commonly called as allergic or hypersensitivity reaction.

What is Allergy

Allergy is a condition of the immune system which causes hypersensitivity. This condition usually caused by exposures to a substance called an allergen.

An allergen maybe pollen, food, drug, insect bite, antibiotic etc.

An allergen triggers activation of immunoglobin class E(E- Antibodies)  which causes the mast cell to degranulate and release chemicals  called histamine and leukotrienes.

Process:

When a person encounters an allergen for the first time, his immune system reacts and antigen presenting cells present the allergen to TH2 lymphocytes which are the subset of T-Cells.  TH2 cells produce specific signal proteins called as Interleukine-4.  IL- 4 signals TH2 cells to interact with B- Lymphocytes and produces Ig-E antibodies. IgE antibodies circulate in the blood and bind to the receptors on the basophils and mast cells.

If the same person exposed to the the same allergen for the second time, IgE produced against the allergen gets Activated which in turn activates basophils and Mast cells. These cells undergo lysis to degranulate themselves which results in the release of Histamines, leukotrienes and other chemicals into the surrounding tissues, this causes the allergic reaction.

Common Allergic Symptoms and diseases

Asthma

Hayfever

Conjunctiva

Sinusitis

Wheezing

Reddening of Eye

Skin Rashes

Abdominal pain

Common Allergens

Pollens and Dust

Drugs

Food

Cosmetics

Latex or rubber materials( Which are in direct contact with skin)

Antibiotics( penicillin)

Treatments

Administration of immunosuppressants like antihistamines, antiepinephrines, antiprostaglandins and antileukotrienes.

Prevention

Avoiding any allergen if mild symptoms are suspected.

Taking Foods that are rich in antioxidants, zinc.

Avoid giving solid foods for infants till they reach 5 years.

Avoid drugs that suppress healthy immunity( not IgE mediated)

Hygenic practices can avoid airborne allergens.

Facts to note

90% of the food allergies are caused by Milk and milk products, meat and meat products and wheat

Some food allergens cause rapid and extensive reactions and can cause death.

Most allergies are hereditary.

Identical twins will be allergic to some allergens.

Stress enhances the number of allergies.