Befriending the Allergens

Before ordering  Chinese food at least some of us  put in a  rider, to the cook,  "No MSG please".  And  then there are others who  would stay away from peanuts or egg.   Few others  move around with a swollen face and leaky nose during spring.  Ah we are facing  ALLERGY 

So what causes of allergy?  Allergy is human body's natural and immediate reaction  when it spots  something foreign/ alien ( technical term Allergen) in its radar screen, be it air borne or food borne. A whole battalion of defense forces roll out of their resting dens and unleash their weapons and the body suffers.

Allergies of all types are on the rise in the West and billions of dollars are being provided as support grants to scientists to unravel the enigma.  Progress has indeed been made but more needs to be done.  Thus we now know that . while  leucocytes might be the common term for the defense force,  there are very  specialized warriors like the neutrophils , eosinophil, basophils, lymphocytes, the T cells, natural killer cells ..................  Checks and counter measures are also in palce. For example another set of cells  called Regulatory T cells  ( or Suppressor T cells )  sees to it that this  killing spree  doesn’t go unchecked and helps to bring about some sort of   peaceful coexistence between the warring groups. 

There have been umpteen discussions on whether allergies are  inherited or acquired  at a later stage in life  as a consequence of life style, eating habits etc.  Well  it could be both. If there is a family history sure enough  there indeed  is a predisposition.  After all  isn’t the  foetus   protected  by the  antibodies  present in  mother's blood?  

November 24th issue of Nature magazine carries a special section on Allergies.  The demographic analysis brings in interesting results.

·         Allergies in general are on the rise in the developed world

·         Asthma is extremely common in North America, Australia & South America

·         Asthma is lowest in parts of Russia,  China

·         Food allergies are  negligible in India though asthma is prevalent.

To get a better perception of the Nature Vs Nurture argument we need more information on the subsets: such as how do the first, second and third generation immigrants in the developed world fare?.  This is awaited.

But the first  bullet is intriguing. Why the West is more prone to allergic diseases?  With cleaner living conditions and higher standards of living  one would have expected  the  West to have healthier trends?  That,  too much hygiene could indeed be an issue was first pointed out in 1989 by Doctor David  Strachan (Department of Public Health Sciences, St George’s Hospital Medical School, London, UK). Since then this is known as the  Hygiene Hypoythesis . 

Too much of antibacterials and antibiotics  eliminate not only the pathogens but also the good ones.  The human body,  thus robbed off the  opportunity to make an acquaintance with the microbial  community,   classify and confront them en masse as aliens/antigens. So the need of the hour is to strike a balance.  Shutting off the enemy completely may not be such a good idea; instead confront them early on so that  we can get to know them, devise a strategy and suitable weapons. [ Isn't  this the very  idea behind  vaccination?]

  

Studies are on to introduce allergy sufferers to miniscule amounts of the allergen and thus slowly develop their immunity.     Duke University Medical centre at Durham, NC USA and University of Cambridge, UK conducted independent experiments on peanut allergy.   In both studies  (groups size of 20-25)  kids   prone to allergic reactions with peanuts were  encouraged to eat   minute amounts of peanut  flour , the dose increasing daily over a 30 week period. At the end of the trial period  several of them could eat upto  30 peanuts without any harmful side effects. 

Though  this trick is known for centuries , it will take time  to transform this into a proper form of  therapy.   But for the time being,  what is your peanut tolerance? 

REFERENCES

Nature  24 November 2011 pages S1- S27.

David P Strachan Family size, infection and atopy: the first decade of the “hygiene hypothesis” Thorax 2000;55(Suppl 1):S2–S10