Cat dander triggers allergic responses

Immune system's extreme reaction to cat allergen previously poorly understood; study could lead to new treatments for those with cat and dog allergies We are hopeful that our research will lead to new and improved treatments for cat and possibly dog allergy sufferers - Clare Bryant New research reveals how the most common cause of severe allergic reactions to cats, the Fel d 1 protein which is found in cat dander, triggers an allergic response. Scientists have discovered that when the cat protein Fel d 1 is in the presence of very low doses of the ubiquitous environmental bacterial toxin, lipopolysaccharide (LPS), it activates the pathogen recognition receptor Toll-like receptor 4. Until now, it was not understood how Fel d 1 generated such a large inflammatory response in the immune system. Allergic reactions are the result of the immune system overreacting to a perceived danger. Instead of identifying and responding to a harmful virus or bacteria, it misidentifies different allergens, including dander (microscopic pieces of animal skin often accompanied by dried saliva from grooming), as dangerous and mounts an immune response. In order to find out how Fel d 1 triggers these allergic reactions, the researchers exposed human cells to cat and dog dander proteins in the presence or absence of low levels of LPS. The researchers found that when the bacterial toxin LPS is present, it increases the signalling to the body's immune system, intensifying the body's inflammatory response to the cat protein Fel d 1.