Australian scientists discover reason for extreme allergic reactions

Australian scientists believe they have discovered why some people experience extreme allergic reactions and their find could lead to new treatments for what seems to be an increasingly common problem.

The scientists from the Garvan Institute of Medical Research in Sydney have identified a process which may explain the extreme allergic reactions some people suffer which is a synergistic encounter between two molecules - the researchers say by silencing at least one of these molecules, it may be possible to treat allergies.

These molecules, IL-4 and IL-21, are cytokines or 'chemical messengers' which are produced by immune cells known as T cells - T cells use cytokines to communicate with B cells, which then make antibodies.

The researchers found that when IL-4 and IL-21 are involved in the same 'conversation' with a B cell, they stimulate the production of large amounts of the antibody class known as immunoglobulin E, or IgE.

IgE is an antibody which is normally very strictly regulated by the body and is present in only very small quantities and offers protection against parasites - however the damage occurs when the body produces too much causing conditions such as asthma, dermatitis and rhinitis.

Lead researcher Dr. Stuart Tangye, a B cell biologist, says IgE is such an efficient molecule that too much of it can be dangerous and high quantities tend to over-activate other immune cells and it's the action of those other cells that can be damaging.

Dr. Tangye says it has been known for many years that IL-4 can drive IgE production in humans and mice but says their research shows that IL-21 also stimulates production of IgE by human B cells, but by using an entirely different pathway.

Dr. Tangye, says people with allergies tend to have high levels of IgE in their blood, and it is the action of the these two molecules together which tells the body to make high levels of these antibodies, and it is this interaction which is important.

Dr. Tangye says the discovery gives drug researchers a new target for anti-allergy therapies, as it is now know that therapies or treatment for allergies would be best served by neutralising one or both of those molecules rather than just one, which has been a strategy for many drugs in the past.

The research is published online in the international publication Blood.