Friday, Oct. 29th, 2010

How Allergies Develop


Develops in two stages:

1. The first exposure to the allergen causes sensitization (you get sensitive).

2. The following exposures of the same allergen cause allergy symptoms.

• Histamine – a chemical that reacts to an allergy

• We take anti-histamine when we get allergies to fight them off



The Details

1. Allergen enters the blood stream.

2. B cells make the antibodies

3. The antibodies attach themselves to the mast cell.

4. Allergen binds onto the antibodies on the mast cell.

5. Histamine is released and starts causing allergy symptoms.

Allergens usually tend to enter through the nose and the throat so symptoms are most abundant in these areas.

Anaphylactic shock – sudden releases of inflammatory chemicals into the body of people with extreme sensitivity to certain allergens such as:

• Bee stings

• Peanuts

• Shellfish

So what happens?

Blood vessels expand greatly causing a great drop in blood pressure, a condition also known as shock.

Anaphylactic shock can be fought off with injections of epinephrine (adrenaline).



Common Autoimmune Diseases

Rheumatoid Arthritis – causing damage and inflammation of bone joints due to T-cell attack

Juvenile Diabetes – a cell-mediated attack of insulin that produces cells in the pancreas

Multiple Sclerosis – T-cells attack the myelin sheath (fatty tissue) of neurons

Lupus – immune attack on skin and vital organs

Every disease or infection has a different reaction depending on how weak or strong your immune system is.



Immunological basis for organ/skin graft rejection?

Transplant Rejection – an immune system recognizes the donor’s cells or organs as foreign and starts attacking

Donors with self proteins that match the recipient’s as closely as possible are used in order to minimize rejection.

Drugs are used to hold back to suppress the immune system. The donors and recipients may not be related.



Immunodeficiency Diseases

Examples:

1. SCID (Severe Combined Immunodeficiency) – a case where someone does not have functional T and B cells; as a result, they do not have specific responses.

2. Hodgkin Disease – a type of cancer that affects the number of lymphocytes, affecting the T and B cells.

3. AIDS/HIV



AIDS (Acquired Immune Deficiency Syndrome)

HIV attacks the helper T cells that activate T bells and B cells.

Since 1981, AIDS has killed more than 20 million people, and 40 million people are living with the virus. Over 1/3 of the adult population in Africa has been infected as well.

Death is usually not a result of HIV, but because of other life threatening infections.



Next Scribe: Yunsu Yu