Allergy and Histamines - What they are…What they cause

Re post from Nutri-Living Blog and About.com/Allergy

Histamine is found in plant and animal tissue and is released from mast cells as part of an allergic reaction in humans. Release of histamine stimulates gastric secretion and causes dilation of capillaries, constriction of bronchial smooth muscle, and decreases blood pressure.

Histamines are released from mast cells as an allergic response to abnormal proteins found in the blood. The mast cells are found in connective tissue that contains numerous basophilic granules and releases substances such as heparin and histamine in response to injury or inflammation of body tissues.

Mast Cell

Understanding Mast Cells and Immunity

Immune cells communicate by releasing chemicals messages or mediators. These chemicals carry messages from one cell group to another and invoke the most powerful of whole-body defense responses, which cause many of our symptoms. When you develop bacterial or viral infections, immune mediators produce fever, headache, generalized aching, fatigue, weakness and clouded consciousness.

The general impact of these chemical messages is to amplify a small triggering event into a large inflammatory response. We used to call this the “Philadelphia Effect” after Philadelphia police burned down several city blocks by using a smoke bomb to flush out some alleged terrorists from one apartment. If planet Earth is thought of as an organism, you can make interesting analogies with immune events.

Hypersensitivity attacks are similar. A person may be doing all sorts of terrible things to his/her body over many years until one day, apparently out-of-the-blue; he/she drops dead of anaphylaxis or a heart attack. If a reactive body, or country, makes it through the initial blaze, a chronic inflammatory state may set-in. This is the cell-mediated immune response. We can now compare the smoldering tissue destruction of diseases such as rheumatoid arthritis or lupus with oil spills, oil-well fires, socio-economic disruption and other environmental devastation, following the Gulf War for example as prolonged and destructive, just as we describe immune activity often as autoimmune disease.

How severe can histamine reactions be?

It has recently been discovered that histamines may play a much larger roll in human disease than once thought. In the past, histamine production was blamed on some very common allergic reactions such as hay fever, bee sting reactions, and anaphylactic shock.

In recent studies, histamine involvement in chronic inflammatory and degenerative diseases such as Lupus, Arthritis, Gulf War Syndrome, Fibromyalgia, Leaky Gut Syndrome, and some skin disorders like Psoriasis and obscure Rashes, has come to light as causes of chronic inflammatory responses to abnormal proteins in the blood of chronically ill patients!

What is an Allergy?

The topic of allergies has become routine in our lives, and certainly most everyone has an idea of what an allergy is. Allergies are so common a subject in fact, it seems acceptable to discuss your allergies at a cocktail party with strangers.

An allergy is an abnormal reaction by a person's immune system against a normally harmless substance. A person without allergies would have no reaction to this substance, but when a person who is allergic encounters the trigger, the body reacts by releasing chemicals which cause allergy symptoms. However, just because there is a cause and effect between exposure to a substance and the development of symptoms does not always mean that a person is allergic to that substance. For example, medications have known and expected side effects; a person experiencing one of these side effects is not necessarily allergic to that medication.

What is Happening During an Allergic Reaction?

During an allergic process, the substance responsible for causing the allergy, or allergen, binds to allergic antibodies present on allergic cells in a person's body, including mast cells and basophils. These cells then release chemicals such as histamine and leukotrienes, resulting in allergic symptoms.

Watch a video demonstrating the allergic response.

How do Allergies Start?

The allergic person can make allergic antibodies, or IgE, against a variety of allergens, including pollens, molds, animal danders, dust mites, foods, venoms and medications. This occurs through a process called sensitization, where a person’s immune system is exposed to enough of the allergen to make the body produce allergic antibodies to that substance.

With later exposures, that same allergen binds to its corresponding IgE on allergic cells, and the body reacts with symptoms of allergies. Allergic symptoms can vary somewhat with the type of allergen and route of exposure (airborne pollen exposure may cause different symptoms than eating a food to which you are allergic).

Learn how to avoid allergic triggers and avoid specific food allergens.

When and Why do People Develop Allergies?

It is unknown why some people develop allergies and some don’t. Allergies seem to run in families, and in some cases family members can share allergies to specific foods or medications. It appears that the allergic response was once meant to protect the body against parasitic infections, although now seems to be an abnormal response to non-infectious triggers.

Allergies can occur at any time during our lives, but are more common to occur during childhood or young adulthood.

Next: Find out what symptoms indicate that you may have allergies.