Mast Cells & Allergies

Flowering trees can torture allergy sufferers.

Although allergic responses are quite complicated, mast cells play an intricate role because they are part of the body's immune system. They work with other immune system cells, the endocrine system and the nervous system to maintain balance in the body. When an allergen enters the body, mast cells assume the allergen is harmful and release several chemicals to fight against it. The presence of these chemicals is responsible for the irritating allergic symptoms, such as runny nose, itchy eyes and sneezing. They may also cause tightening in the throat and lungs, leading to asthma.

Mast Cell Structure

Mast cells are oval-shaped, fluid-filled cells that specialize in immune system responses, such as inflammation, injury and allergic reactions. They contain granules that house a number of chemicals and enzymes that are released into the tissues when needed. Thought to be created by the bone marrow, mast cells leave the bone marrow in stem cell form and mature at their final site.

Location

They live in the mouth, conjunctiva, nose, skin, mucous membranes and the fibrous connective tissue supporting the body's organs and other tissues. They are also found near blood and lymphatic vessels, in the digestive tract, urinary tract and respiratory system.

Role of Mast Cells in Allergic Reactions

In response to an allergen, mast cells release histamine, serotonin, bradykinin and heparin from coarse granules within the mast cell. These chemicals each have a separate function in the allergic response. They may control the severity of the reaction and the time lapse between the allergen exposure and the allergic symptoms.

Histamine

Histamine affects the body in two ways. It widens the blood capillaries and increases their permeability so that more fluids can pass from the blood to the tissues, a process that causes swelling. The presence of histamine also causes the involuntary muscles in the lungs, heart, stomach, bladder, intestines, and blood vessels to contract.

Serotonin

Serotonin is a key factor in food allergies. Most of the body's serotonin resides in the mucous membrane cells of the gastrointestinal tract. Although it performs differently than histamine, its presence still results in inflammation.

Bradykinin

Bradykinin adds to the inflammation, but also serves two other functions. It stimulates nerves to cause pain and widens the peripheral arteries, which leads to a drop in blood pressure.

Heparin

Heparin inhibits the action of an enzyme essential to blood coagulation, which may increase blood flow to the inflamed site.

References

• "Allergy Relief and Prevention, Third Edition"; Frances Taylor, MA., Jacqueline Krohn, MD., Erla Mae Larson, RN; 2000
• MedicineNet.com: Defintion of a Mast Cell