Impaired immunity

• Antigens are cell markers that induces a state of sensitivity after coming in contact with an antibody; any substance that causes the body some type of harm, thus setting off this specific reaction.
• Antibodies are immunoglobulins that develop in response to an antigen; also called immune bodies; proteins that the body produces to react to and render the antigen harmless.
• An allergen is an environmental substance that causes a reaction.
• An allergy is the state when the immune response is too intense or hypersensitive to an environmental substance.
• Autoimmunity: the state when the immune response attacks itself. 
• Immunodeficiency: the state when the immune response is unable to defend the body due to a decrease or absence of leukocytes, primarily lymphocytes. 
• AIDS: acronym for acquired immunodeficiency syndrome. 
• Organ rejection is the process in which the body’s immune system recognizes a transplanted organ as foreign and attacks it, leading to organ death.