Friday, May 26, 2006

Allergies: How They Work and Why We Suffer

by (Class of '06)
By Hannah

Do you struggle with allergies? Are you allergic to certain foods? Or do you get congested, have itchy throats, or sneeze simply from walking outside? Why do we get allergies, and what makes us suffer?

Allergies are triggered because of a hypersensitive immune system. In a hypersensitive immune system, harmless substances are mistaken to be dangerous and are then attacked.

Lymphocytes which are white blood cells are present in the immune system. Two types of lymphocytes exist throughout the body; B-cells and T-cells. A lymphocyte’s job is to protect the body from foreign substances like bacteria and viruses. However, in a hypersensitive immune system, Lymphocytes can not always distinguish whether something is a threat and make mistakes, causing an allergic response.

Lymphocytes identify surface markers on molecules to determine if they are foreign to the body. When a lymphocyte cannot identify a substance, the B-cell (lymphocyte) which is capable of producing antibodies, travels to the lymph node where it transforms into a cell and produce IgE antibodies which fight the threat. The IgE antibodies fight foreign bodies and ultimately cause allergies and allergic reaction like hives, itching, runny nose, sneezing that many people suffer from.

When the B-cell mistakes a foreign substance as dangerous the B-cell, as explained earlier, produces IgE antibodies which fight the intruder. The IgE antibodies attach themselves to white blood cells that contain histamine. Histamine is a substance that helps fight infections in the body. The process of attachment is called Sensitizing Exposure, and the process takes about ten days to complete. Once the process is complete however, the next time the lymphocytes recognize the intruder a process known as the allergic cascade occurs.

In the allergic cascade, the IgE antibodies (lymphocytes that are there to protect the body from foreign substances) that are bound to the white blood cells containing histamine recognize the surface markers on the foreign body. The antibodies then attach themselves to the surface marker of the allergen (foreign substance detected by the lymphocytes). The attachment between the antibodies and the surface marker of the allergen alerts a group of proteins known as the complement complex. A primary protein attaches to the site and starts a sequence of protein attachment. The intruding cell is defeated once the sequence and chain of proteins is finished.

Destroying the intruding cell however, also destructs the white blood cells containing Histamine that were attached to the intruding cell.

When the white blood cells are destroyed, the histamine that the cells carry is released into the body’s tissues and blood. When the histamine is released, the surface blood vessels become dilated, resulting in lowered blood pressure. The dilation enables fluid to fill the gaps, causing the allergy symptoms that we all know and love.

Other, more serious allergic reactions like anaphylactic shock, which depending on the situation and reaction, can result in troubled breathing, swelling, organ damage, and blocked airways, is caused by a systematic reactions. In systematic reactions, the release of histamine causes capillaries all over the body to dilate, instead of in just one area of the body.

It is amazing what goes on in our bodies. It is at least comforting to know that our allergies are the result of an immune system overly eager to keep us safe.


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