Tuesday, April 5, 2011

Cat Allergy from the Allergen Fel d 1

In response to a patient's question, what is Fel d 1?  
Let's go backwards a few steps.  People with allergies to cats are specifically allergic to compounds produced by cats.  The World Health Organization and the International Union of Immunologic Societies (IUIS) have classified the known allergens from cats by the group name Fel d (an abbreviation for Felis domesticus or house cats) with the specific allergens numbered from 1 to 8 currently.  Fel d 1 has been determined to be the major cause of symptoms in most patients with clinical allergy to cats.  Fel d 4 is another allergen, but very little has been written about it.  A PubMed search showed only 1 article with Fel d 4 in the article's title.  An overview of cat allergy can be found on Wikipedia.  I caution readers, though because about half of the references are to lay journals, and not to be a snob, but not from scientific journals.

I'd like to emphasize some facts about Fel d 1.  
First, the major source of Fel d 1 is skin's sebaceous glands then cat saliva.
Second, with a cat in the home, the size of particles found in the air ranges from greater than 9 microns (49%) to less than 4.7 microns (23%).  The latter is significant for 2 reasons.  First, any particles less than 5 microns are light enough to float in the air currents in a room almost indefinitely.  Second, any particles less than 5 microns can reach almost to the deepest parts of the lungs with even normal respiration.  This could cause a lot of inflammation and asthma.  HEPA filters are very effective at reducing the allergen levels, once the cat is removed.
Third, Tovoy et al (J Allergy Clin Immunol 2001) had an article published titled "Effectiveness of laundry washing agents and conditions in the removal of cat and dust mite allergen from bedding dust".  They concluded washing the bedding in warm water (25 degrees Celsius), with any type of detergent, with no benefit from added "enzymes", for more than 5 minutes was sufficient to remove most cat allergens, although hot water (60 degrees C) was more effective.

Now for some unwanted advice for my patients and critics, please get rid of your indoor pets and wash your bedding once per week in hot water.

This has been a quickie summary from The Allergy Dude.

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