Anaphylaxis

Anaphylaxis is a violent allergic reaction of the whole body which can result in death. During anaphylaxis, the allergic person's throat swells so much that she or he cannot breath, while internal organs may start to shutdown. The immune system's attempt to rid the body of a particular substance actually turns against the body itself.

When research on the immune system was progressing in the 1800s, most scientists thought that the body's reactions to invaders were always protective. While researching experimental smallpox innoculations in 1798, Edward Jenner (1749-1823) observed that patients given a second shot often suffered violent reactions. Despite this risk, people were more afraid of the disease than possible inoculation side effects. Jenner's experimentation, which included inoculating subjects with both cowpox and smallpox, eventually led to the development of a successful—and safe—smallpox vaccine.

The first complete study and description of negative immune responses was produced by two Frenchmen, physiologist Charles Richet and physician Paul Portier (1866-1962). During a scientific cruise on the yacht of Prince Albert of Monaco (a small principality on the Mediterranean Sea), Albert suggested that Portier and Richet study the poison (toxin) produced by the tentacles of the Portuguese man-of-war, a jelly-fish. Back in France, the two men continued their studies with extracts of toxin from a sea anemone (a flower-like marine creature). While looking for a toxic dose level, they injected dogs with sea anemone venom. Dogs that survived were given time to recover and then reinjected. Richet expected that the first exposure to the toxin would create a certain amount of immunity in the dogs, the same way that getting a virus gives someone immunity to another encounter with the same disease. Instead, the initial exposure made the dogs hypersensitive. A second, much smaller dose of toxin quickly killed them. Since this result was the opposite of a protective immune response, or prophylaxis, Richet named the hypersensitive reaction anaphylaxis. Richet's identification of anaphylaxis won him the 1913 Nobel Prize for medicine.

After further research, it was discovered that many substances people are allergic to, particularly foods and toxins from animals (such as bee venom), can cause strong reactions. This knowledge provided a valuable warning to physicians engaged in serum (anti-poison) therapy. The researchers began checking patients for possible sensitization before injecting potentially toxic amounts of serum. Those patients with an initially severe reaction to an allergen (or allergy-causing agent) were advised to carry epinephrine (an artificial hormone) to inject immediately if they had a severe reaction.