Austrian researchers in a world first have successfully engineered an allergy vaccine

Aug 9 2004

Austrian researchers in a world first have successfully engineered an allergy vaccine using a genetically modified version of the birch pollen allergen.

This new research is reported in the current issue of the Proceedings of the National Academy of Sciences.

An allergy is a reaction to a substance that occurs through a change in the immune system caused by the production of antibodies, and is usually experienced by only a small number of people exposed to a substance.

The antibodies belong to the immunoglobulin family of proteins and are designated into five major types; Immunoglobulin A, D, G, M, and E. IgA antibodies are found in saliva and tears and serve to protect the respiratory and gastrointestinal systems. The role of IgD is uncertain. IgG, often called the "blocking antibody," protects people from an allergy attack and is also responsible for protecting newborns during the first months of life. Both IgG and IgM activate the complement system, a group of blood enzymes that also play a role in controlling infection.

An antigen producing an allergic reaction is defined as an allergen. Allergens cause the immune system, specifically white blood cells, to produce IgE antibodies that attach themselves to mast cells or basophils. Mast cells are usually found in the respiratory and gastrointestinal tracts and the skin; the basophils are found in the blood. As many as 500,000 of these Y-shaped IgE molecules may collect on a single cell.

When the allergen and the IgE antibody combine by bridging the area between IgE molecules, these cells release potent chemicals such as histamine, which produce many of the familiar allergic symptoms such as runny nose, watery eyes, itching and sneezing. The cell membranes of the mast cells and nearby tissue cells give off arachidonic acid, which interacts with enzymes and produces additional chemicals called prostaglandins and leukotrienes. The leukotrienes have been identified by researchers as substances 5,000 to 10,000 times more powerful than histamine in causing inflammation and airway obstruction.

Allergy shots are commonly used to treat allergies, but they have drawbacks.

The research focused on 124 adults who all received a vaccine before peak birch pollen season started. The group was screened year round for antibodies that indicated the presence of an allergic response.

The researcher team found increased levels of IgG antibodies in the people who had received the vaccine. Combined with a decrease in IgE antibodies the research time concluded that the vaccine had been working.