Acquired Immunity
Acquired (adaptive) immunity develops when the body is exposed to various antigens. It involves a specific type of white blood cells called lymphocyte. There are two types of lymphocytes.

B lymphocytes (also called B cells) produce antibodies. Antibodies attach to a specific antigen and make it easier for the phagocytes to destroy the antigen. T lymphocytes (T cells) upon encountering antigen activate a number of effective systems which ultimately destroy the antigen. At the same time, the response creates the reserve of the memory cells for future demand. This allows the immune system to respond faster and more efficiently the next time you are exposed to the same antigen.

Body’s Response to Allergens
When an allergen enters the body of a person with a sensitized immune system, it triggers antibody production. Histamine and other chemicals are released by body tissues as part of the immune response. This causes itching, swelling of affected tissues, mucus production, muscle spasms, hives and rashes, and other symptoms. Symptoms vary in severity from person to person.

The part of the body contacted by the allergen will partly also affect symptoms. For example, allergens that are inhaled often cause nasal congestion, itchy nose/throat, mucus production, coughing, wheezing, or similar symptoms. Food allergies often include abdominal pain, cramping, or similar symptoms, although the whole body may be affected when the food is absorbed. Allergies to plants often cause skin rash. Drug allergies usually involve the whole body. Many disorders are associated with, triggered, or worsened by allergies. These include hay fever, eczema, asthma.

Common allergens include environmental agents that contact the skin, breathing passages or the surface of the eye. Food and drug allergies are common. Allergic reactions can be caused by insect bites, jewelry, cosmetics, and almost any substance that contacts the body.

Food Allergy or Just Sensitivity
Certain foods are often erroneously blamed for being allergic foods. Rather than being allergic, they have naturally occurring histamines within the foods themselves. Examples of foods with natural histamines are wine, chocolate, strawberries, tomatoes.

If you are sensitive to one or more of these foods, you might get an itchy rash or a headache after eating them. But if you were tested, your doctor would probably not find any allergic skin or blood results. The exception is wine, some of which is made with preservatives called sulfites and can cause rare but severe allergic reactions. (That’s why on wine bottles you see warnings about whether or not the wine contains sulfites.)

Some patients say they are allergic to milk. However, it frequently turns out that the stomachache, gas and bloating are caused by the inability to properly digest milk sugar (lactose) due to an enzyme deficiency. The lactose ends up fermenting in the person’s intestine causing discomfort. Eating yogurt or cheeses, drinking lactose–free milk, or taking lactase tablets or acidophilus resolves most of the problem. Some patients believe that they are allergic to wheat and sugar. Again, this is often undetermined. However, many of these people are indeed sensitive to these foods and do feel better off them. Some parents believe their children get fewer ear infections and are less irritable off certain foods.

Always remember that real food allergies can be dangerous, and that potential food allergies should be diagnosed and treated by a physician knowledgeable in this field of medicine. Hopefully, after reading this article you will be better able to determine whether or not you or someone you know might have a food allergy, and be more aware of the difference between a food allergy and a food sensitivity.