It's summer time, and that means that the pollen count is high again. Many people are allergic to different kinds of plant pollen, like that from ragweed. The most common allergic response to pollen is usually increased mucus production and watery eyes, but it can get much worse. Allergic responses can range anywhere from minor itchy eyes to inflammation of the lungs that can send you to the hospital.
Allergies are caused by usually harmless antigens that enter our body and cause an overactive immune response in people who are hypersensitive. The antigens that cause allergic reactions are called allergens. When an allergen enters the body, IgE (Immunoglobulin E) antibodies are created to fight of the foreign invaders. These antibodies will activate certain kinds of white blood cells called mast cells and basophils. When activated, these white blood cells will release chemicals such as histamines and serotonin that can cause constriction of smooth muscles (which can cause difficulty breathing), blood vessel dilation, and swelling. Allergies are called type 1 hypersensitivity, or immediate hypersensitivity. There are 4 kinds of hypersensitivity.
Most people get severe rashes when touching poison ivy, but this reaction is actually an allergic reaction. Poison ivy, and other plants such as poison oak, contain an oily substance called urushiol which causes the itchy and inflamed rashes that most of us get when touching poison ivy. This means that some people don't experience anything when they touch these plants because they aren't allergic, but allergic reactions can be developed, so it is never a good idea to go around touching poison ivy.
Many allergies, especially those caused by food, are responses to certain kinds of proteins. The most common food allergy is a peanut allergy. Peanut allergies can be quite severe, causing anaphylaxis which can be life threatening. Anaphylaxis can cause hives, gastrointestinal distress such as vomiting, trouble breathing, and a whole host of terrible things. Allergy causing proteins can be found in many places, from the whites of eggs to latex gloves, which makes them a common allergen.
It is true that allergies have a strong genetic factor. Twins have a 70% chance of having the same allergies, and parents with allergies are likely to have children with allergies. However, the children of allergic parents don't necessarily inherit a specific allergy, they inherit the likelihood to develop an allergy. There is allergy discrimination between genders. Overall, males have a higher risk of developing allergies than females, but females have a higher risk of developing asthma. Not all allergies are based on genetics however, your environment can have a significant impact on if you develop allergies, and what kind of allergies you do develop. Pollution, illnesses and repeated exposure can often cause a person to develop allergies even if they do not have a genetic disposition to allergies.
Allergies can be treated with anti-histamines to reduce swelling and counteract the effects of mast cells. Other treatments such as steroids are immediate responses to allergic reactions, but immunotherapies exist that can help to rid a person of their allergies altogether.