Immunotherapy for allergic diseases (1)

 

 

Allergic diseases are some of the most common diseases in Hong Kong.  It has been estimated that up to 50% of school children suffer from symptoms of rhinitis, while about 15% of them have asthma and about 10% have eczema.  The incidence of allergic diseases is also increasing around the world, as a result of changes in our lifestyle and our environment.

 

Allergic rhinitis/conjunctivitis is a common problem that many sufferers simply ignore.  The symptoms include sneezing, itchy nose, itchy eyes, runny nose, watery eyes, congestion and post-nasal drip.  However, severe cases can be quite debilitating.  Children with allergic rhinitis have been shown to suffer from poor sleep, impaired learning, bad temper and hyperactivity.  Adults with allergic rhinitis are at risk of disorders of mood and sleep.  Severe allergic rhinitis might become complicated by sinus and middle ear infections, worsening of asthma, and might affect facial and dental development in children.

 

The cause of allergic rhinitis in any individual is dependent on his/her living and working environment.  In temperate climate, pollens are the most common causes.  However, in subtropical climates such as Hong Kong, indoor allergens such as house dust mites, mould spores, cockroaches and animal dander are the most common causes.  Exposure to allergens in the work environment is also very important.

 

Why do people develop allergies?  When we are first exposed to a foreign substance, through our skin, our respiratory tract or GI tract, our immune system will strive to recognize this substance.  In most cases, our immune system recognizes that these substances are harmless and ignores them.  This is a process called immunological tolerance.  Not only does the immune system ignore these antigens, it actually develops a response that actively suppresses any reaction to the antigens.  This active suppression can be passed on from one experimental animal to another by transferring immune cells called T cells.  In allergic individuals, this mechanism somehow failed to work for certain antigens (allergens), and they develop an immune response every time they encounter these antigens.  This immune response leads to allergic symptoms.

 

 

Reference information: hkucc.hku.hk

 

The information aims to provide educational purpose only. Anyone reading it should consult
physician before considering treatment and should not rely on the information above.