While studying
immunology in college, we had learned that our immune cells, upon infection and
subsequent successful immune response create memory cells that persist in the
body and through a highly selective process get mature and protect our body from
future infections of same pathogen. This is also a basis of vaccination against
various illnesses caused by different pathogens.
The common sense says that if there is memory it aught to suffer from forgetfulness. The forgetfulness of
immune system came to my mind on several occasions. Whenever, after spending a few
years at a stretch in the western countries where high levels of hygiene is practiced,
we visit our natives in the India, our first worry is to not consume unfiltered
water. Most of the energy, and money too, goes in amassing bottled or filtered
water. If it’s not available in the local market, which is the usual scenario
because no one buys them there and thus vendors do not sell them, then next best
thing is to boil the hand-pump water, tap water being rarity in villages even
in twenty first century India.
But if by mistake or in
desperation, because water is necessary to live, we consume the normal water,
most of our energy, and money too, goes in amassing medicine to combat the aftermath i.e. loose motion or diarrhoea.
What happens that the water we had grown up
drinking becomes source of all trouble?
Image source: bigstock.com
The forgetfulness of
immune system came to my mind again when a group of scientists recently
suggested that in the young children the repeated cause of illness could be that their
immune system is forgetful.
World health organization
(WHO) says that worldwide one third of total infant mortality is due to infectious
diseases! This happens besides the strong vaccination programs being run by the
government’s public health department.
As I recalled earlier about
memory immune cells created during the immune response or vaccination that get
mature by a highly selective process, they also require presence of pathogenic antigen
for this selection process. It turns out that in children memory rapidly vanishes
in the absence of booster dose of vaccine. The non-compliance of vaccination
becomes fatal for these children.
The answer to
forgetfulness of adult immune system could be that when we are away in
societies where the hygiene level is high, our memory immune cells do not get to see
the antigens and they tend to get negatively selected out, a kind of 'out of sight out of mind' thing. Having no specific
memory immune cells, these same pathogen becomes “new” and body responds to it
as if it is seeing them for the ‘first time’.
Ideally, once a vaccine
shot given at birth should be sufficient for long lasting or say life-long
protection from disease, but no such vaccine exists. And we do need to follow-up
for the vaccination shots to boost-up the child’s immune system and keep it
alert and ‘mindful’.
In case of adults, it is
probably because immune system is a dynamic process and is shaped by the
environment we live in. It's job is to protect us from the pathogens lurking in
our surrounding. If, for some reason, we fail to interact with the ‘environment’
our immune memory cells raised against pathogens in that environment get
negatively selected out from our body and our immunity become forgetful of
those antigens.
