Protein a possible key to allergy and asth...( Activating a protein found on some i...),Health

Activating a protein found on some immune cells seems to halt the cells typical job of spewing out substances that launch allergic reactions, a study by Johns Hopkins researchers suggests. The findings could eventually lead to new treatments for allergic reactions ranging from annoying bouts of hay fever to deadly asthma attacks.

Previous studies by Bruce Bochner and his colleagues at the Johns Hopkins Asthma and Allergy Center had zeroed in on the protein, Siglec-8, as an important player in allergic reactions. This protein is found on the surfaces of some types of immune cells, namely eosinophils, basophils and mast cells, which have diverse but cooperative roles in normal immune function and allergic diseases. Eosinophils directly combat foreign invaders, such as parasites. Basophils and mast cells store and release substances such as histamine, prostaglandins and cytokines, which signal other immune system cells to ready for battle.

When functioning correctly, these cells are a valuable aid to keeping the body healthy and infection-free. However, in allergic reactions and asthma attacks, the cells unleash an overwhelming response that typically harms the body more than it helps.

The researchers found in previous studies that when they activated Siglec-8 on the surface of eosinophils, the cells promptly died. Expecting the same suicidal response in mast cells, the scientists tested their theory in a new study on human mast cells and mast-cell-containing tissues.

Using mast cells grown in a lab, the researchers used antibodies to activate Siglec-8. We were surprised to see that these cells just sat there happily in their petri dishes and lived on, says Bochner, director of the Division of Allergy and Clinical Immunology at the Johns Hopkins University School of Medicine.

With their initial theory disproven, Bochner and his colleagues suspected that Siglec-8 might be slowing down other cellular processes ba
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