Cytotoxic Hypersensitivity Reactions
Allergy and Anaphylaxis
Allergy and Anaphylaxis are Type 1 Hypersensitivity reactions. They result from antibodies fixing to mast cells and contacting antigen, triggering mediator release. This leads to clinical manifestations. Examples of a localized response would be hay fever or a food allergy. An example of a systematic response would be a bee sting, or penicillin anaphylaxis.
Allergy: Because histamine is one of the mediators, antihistamine drugs are usually effective in treating allergic symptoms. Many allergic persons may be treated by immunizing the person to allergy causing agents.
Anaplylaxis is a severe hypersensitivity reaction which may be life threatening. Common implicated allergens include bee stings, penicillin, nuts, and latex. Exposure may lead to a decrease in blood pressure, circulatory collapse, and severe respiratory distress, restricting air flow in and out of the lungs. Treatment with epinephrine or other similar agents is required. (Crowley, 2014)
Examples of Type 2 hypersensitivity reactions include transfusion reactions, hemolytic disease of newborns, chronic hemoplytic anemia, and certain kidney diseases. In this type of reaction, antibodies formed against certain cells bind to the surface of said cell. The binding creates products that damage the target cell, and form an attack complex that damage the cell membrane. Inflammatory cells are also attracted to the area and cause more damage by releasing destructive enzymes.
Delayed Hypersensitivy Reactions are Type 4 reactions. They are also sometimes known as a tuberculin type hypersensitivity. In these reactions, T lymphocytes are responsible for tissue injury. This commonly occurs with individuals who have been infected with bacillus, and have developed a cell-mediated immune raction. It should also be noted that other bacteria, fungi and parasites may evoke a similar response. Delayed hypersensitivity reactions may also result from exposure to poison ivy, various drugs, chemicals, and cosmetics. The reaction that occurs from this exposure leads to an inflammatory reaction skin condition called contact dermatitis.
Type 4 Hypersensitivity , cell-mediated reactions, require 24-48 hours to develop. This delay is due to the fact that it take the sensitized T cells to accumulate at the site and generate an imflammatory reaction. These hypersensitivity infections are commonly detected by a Mantoux skin test. (Crowley, 2014)
Examples of Type 3 immune complexes are glomerulonephritis, lupus erythematosus, and rheumatoid arthritis. In these diseases, immune complexes form within circulation and are deposited in tissues. These activated components, and the inflammatory cells they attract, damage the tissues. The damage may lead to thrombosis of blood vessels and tissue necrosis. (Crowley, 2014)
Delayed Hypersensitivity Reactions
Immune Complex Disease
Hypersensitivity Reactions
Hypersensitivity is defined as a state of abnormal reactivity to a foreign material, normally including an intense inflammatory reactionat the site of contact with the foreign antigen. Hypersensitivity reactions are classified by how the immune system caused the injury. (Crowley, 2014)
