Until now, medical science has known the cause of allergies (a reaction to proteins) but not why only certain proteins can trigger allergies. Until now, what was known was that certain proteins, such as those in pollen, can render the immune system hypersensitive, causing antibodies (IgE immunoglobulins) to over-react. The reason for the hypersensitivity, however, was unclear.
Franziska Roth-Walter and colleagues at the Messerli Research Institute in Vienna may have found that cause. Using a common allergen, Bet v 1, a birch pollen protein that is easily sythensized in the laboratory, Roth-Walter and her team found that Bet v 1 is very similar to a naturally-occurring human molecule called lipocalin 2 and that both have the same iron-binding properties.
From there, they discovered that when Bet v 1 has bound with iron molecules, the body does not react whereas when the protein has not bound with iron, an allergic reaction takes place.
The significance is in the Bet v 1 similarity to lipocalin 2. Lipocalin 2 manipulates T-helper 2 cells, an immune cell with an iron exchange being part of the process. Bet v 1 can take the place of lipocalin 2 and cause the Th2 cells to over-react.
This coincides with other research into Th1 vs Th2 cells as well as lipocalin 2 cells. This latest research may provide the answer as to why the allergy happens, giving insight into what could be done to prevent them or the reactions they can create.