3. antibodies against usually harmless antigens
immune responses to usually harmless substances
Only if the person is already allergic to that antigen. Not if they are immune to the antigen. The word antigen refers to the protein that joins with the antibody. If the antibody is of the allergic type (IgE) then an allergic reaction will happen and if the antibody is of the immune type (IgG, IgM or IgA) then there won't be an allergic reaction.
An allergy is when a person's immune system perceives something that is usually harmless as a threat to the body and launches an attack called an immune response.
Hypersensitivity is also known as allergic reaction, exaggerated immune response, or allergic sensitivity.
Allergic reactions depend on a person's immune response and biological reactions. This means that all chemicals has the potential to trigger at least one person's allergic reaction.
hypersensitivity
No they are usually a reaction to a stressed out or lowered immune system. They can also occur after being out in the sun or very cold weather for long periods of time.
An allergic reaction i believe.
an allergic reaction
An allergic reaction is an abnormal immune system response to things that are normally harmless to most people. When one is allergic to something, the immune system incorrectly identifies this substance as harmful to one's body. (Substances which cause allergic reactions, such as certain foods, medicines, plant pollen, or dust, are called allergens.)In an attempt to protect the body, the immune system produces immunoglobulin E antibodies. When the IgE antibodies make contact with the allergens, they attach onto it and release chemicals such as histamine into the bloodstream. The histamine causes such allergic reactions as a runny nose, tearing eyes, sore throat, diarrhea, skin rashes, or difficulty breathing and swelling.
No, it is not possible to be allergic to blood. Your immune system violently reacts to the allergens you are allergic to. If anyone were allergic to blood, they'd be dead by now. But it is possible to have a phobia of blood.
An overreaction of the immune system to an otherwise harmless substance is called an allergic reaction. In allergies, the immune system mistakenly identifies the harmless substance as a threat and produces an exaggerated response, leading to symptoms such as sneezing, itching, or hives.